3PL onboarding checklist: from signed to shipping, week by week.

3PL onboarding is everything that happens between signing with a warehouse and its first shipped order: you hand over your data, the 3PL maps your catalog and packing rules into its system, your store gets connected and tested on real orders, and your inventory is received onto the shelf. Plan it as up to four weeks of work, one stage a week, and you'll have room for the things that usually go wrong. A brand that arrives with clean data is live much sooner, and at YNK the stages overlap, so most brands are live in under two weeks.

Below is the plan week by week, what slows each stage down, a checklist you can work through with any 3PL, and how it runs with us.

What onboarding covers, and who owns each part

Onboarding is four jobs, and they happen in a fixed order because each one needs the one before it. The warehouse can't map a SKU it hasn't seen in a spreadsheet, can't test an order for a SKU it hasn't mapped, and shouldn't receive a pallet until it knows what's in every carton on it. Most delays we see come from doing them out of order, usually by booking the truck first because it feels like progress.

You own the data and the decisions: what you sell, how it's packed, which shipping method a customer gets, what happens to a return. The 3PL owns turning those decisions into rules its system follows on every order. If you get stuck on a question, it's almost always one of yours, so it pays to have a single person on your side who can answer the same day.

Week one: send the data pack

Everything later in the plan reads from the files you send in the first week. If you already sent them for a quote (how to compare 3PL quotes covers the quote version), you're most of the way there, but onboarding needs more detail than a quote does.

• A SKU list with one row per variant: SKU code, product name, size and color, barcode, unit weight and dimensions, and units per master carton. Every size and shade gets its own row and its own barcode, because a scanner can only tell apart what's been labeled differently.
• Your last three months of orders, with order date, ship-to zip, units and the shipping method the customer chose. The warehouse uses this to plan labor and to set up the carton sizes your orders really need.
• Every channel you sell on, and which ones the 3PL will ship: your store, a marketplace, wholesale orders, replenishment to another warehouse.
• Your current shipping rules, written out in plain sentences. Which checkout option maps to which carrier service, when a signature is required, what ships together and what ships separately.
• For supplements, gummies, beverage or food-grade goods: the lot number and expiry date for every lot you'll send, and your rule for stock that's close to its date.
• A rough inbound plan: how many cartons or pallets, from where, and the week you expect them to land.

Week one is also when the paperwork settles. You'll want the agreement read and signed, the rate schedule matching what you were quoted, and a target go-live day agreed by both sides. The contract clauses worth reading closely covers what to look for.

Week two: map your catalog and your packing and shipping rules

This is the week that decides how accurate your orders will be. The 3PL loads your SKU list into its warehouse management system, the WMS, which is the software that knows where every unit sits and tells a picker what to grab. Each variant gets a barcode and a location, and look-alike variants should end up in different bins so a medium can't sit next to a large in the same shade.

Then come the packing rules, one per SKU or per product type. A packing rule says how the item travels: which carton or mailer, whether it's bagged, what cushioning goes around it, which way up a bottle stands, and what goes in the box with it, like a thank-you card or a sample. If you don't write these down, the packer decides on the day, and two packers decide differently. Shipping rules get mapped the same week, so a customer who paid for two-day shipping gets the service that delivers in two days.

Ask to see the mapped catalog before week three starts. Say you sell 120 variants: you want a file of 120 rows back, each with a barcode, a packing rule and a location type, and you want to scan through it yourself. A missing barcode is a quick fix at this stage. If it turns up on the dock, it's a relabeling job.

Week three: connect the store and test real orders

Your store and any marketplace accounts get connected to the WMS, so paid orders flow in on their own and tracking flows back out to the customer. What matters here is testing, and a connection that says it's live hasn't been tested yet. Before any real customer depends on it, run a short test plan with the 3PL.

1. 01Place a test order for one unit of one SKU. Check it lands in the WMS with the right SKU, quantity, address and shipping service.
2. 02Place a multi-unit order with two or three different SKUs, including two look-alike variants. Check every line comes across.
3. 03Place an order that should trigger each special rule you gave them: a signature, an insert, a gift note, a bundle that splits into components.
4. 04Have the warehouse pick and pack one of the test orders and send you a photo of the open box before it's sealed. Compare what's in the photo to your packing rule.
5. 05Check that a tracking number posts back to your store and that the customer email goes out the way it does today.
6. 06Cancel an order and edit an address on another, then confirm the WMS caught both before anything was picked.
7. 07If you sell on more than one channel, sell one unit on each and watch the inventory count drop in every channel.

Write down every result. A failed test in week three is a normal part of onboarding, and fixing it now is quick. For the store side in more detail, read how a 3PL connects to Shopify.

Week four: receive the inventory and ship the first orders

Now it's time to book the truck and move the stock. Because the catalog is already mapped, receiving is a matter of counting each carton against your packing list and scanning every unit onto its shelf. Once a unit is scanned to a location, it's sellable, and the stock count in your store should update to match.

How fast this goes depends mostly on how you packed the shipment. One SKU per carton, a label on every carton, a packing list that matches, and advance notice with the counts all make receiving faster. A mixed pallet with no packing list makes it slow, and since receiving is usually billed by the hour, it costs more too. How to send inventory to a 3PL goes through the inbound in detail.

When the counts are in, compare them to your packing list and settle any gap before you switch orders over. Then pick the go-live day. A quiet weekday works well, and the day before a launch or a sale doesn't. If you're moving from another 3PL, keep it shipping until that day, so there's never a morning when nobody is picking your orders. How to switch 3PLs covers the handover from the other side.

For the first week of live orders, look at the dashboard every morning: orders received, orders shipped, anything on hold and why. Most early problems show up as an order sitting on hold for a rule nobody expected, and the fix is a quick call to set the rule.

What slows each week down, and how to avoid it

These are the delays we see most often at each stage. Nearly all of them are data or decisions, which means they're in your hands.

The 3PL onboarding checklist to work through

Work through this with your 3PL and tick each line only when you've seen it done. A promise that it's in progress doesn't count.

• Agreement signed, and the rate schedule matches the quote.
• A go-live day agreed by both sides, and it isn't a launch or sale day.
• One person on your side named to answer questions the same day.
• SKU list sent with one row per variant, barcode, weight, dimensions and units per carton.
• Three months of orders sent, with zips, units and shipping method.
• Lot numbers and expiry dates sent for anything that has them, plus your short-dated stock rule.
• Shipping rules written out: checkout option to carrier service, signature rules, what ships together.
• A packing rule written for every product type, which covers inserts and branded materials too.
• Branded boxes, mailers and inserts on their way to the warehouse, with counts.
• Mapped catalog file returned by the 3PL and checked by you, row for row.
• Store and marketplaces connected, and orders flowing into the WMS.
• Test plan run: single unit, multi-unit, every special rule, a cancel and an address edit.
• Photo of a packed test order checked against your packing rule.
• Tracking posts back to the store and the customer email goes out.
• Inventory counts drop in every channel when one unit sells.
• Inbound packed one SKU per carton, labeled, with a packing list, and advance notice sent.
• Received counts compared to the packing list, and every gap settled.
• Dashboard access working, and you know who to call on the first morning.
• Returns flow agreed: where the parcel goes, how it's graded, when the refund fires.

How onboarding runs at YNK

Most brands are live with us in under two weeks, because the four stages above overlap here. It starts with the 3PL intake, which takes about ten minutes and asks for the same data pack: your SKU list with sizes and weights, where you sell, your packing and shipping rules, a rough inbound plan and your last three months of shipments. Someone from the team replies within one business day, and the proposal, with your start date in it, follows within five, and there's no setup fee.

We map your SKUs, shipping rules and packaging standards into ShipStation, the WMS the whole building runs on, from your own exports. Shopify, including Plus and subscription orders, Amazon and TikTok Shop all connect natively, and every channel draws from one inventory pool. Orders sync in as they're paid, and tracking syncs back to your store, so your customer gets the shipping email the way they do today. The integrations, the WMS and the live dashboard are included, and the dashboard is open to you the day you go live.

Your inventory ships to 465 Mola Blvd, Dock 10, Elmwood Park, NJ 07407. Receiving is billed by the hour, and every unit is scanned as it goes on the shelf, so look-alike sizes and shades never share a bin. Supplements, gummies, beverage and food-grade goods are received by lot with their expiry dates. Once you're live, orders in by noon Eastern (12pm ET) ship the same business day, and before anything goes in a box, someone scans it against the order. That's how pick and pack error stays under 0.3%.

Found shows how short this can get. It was leaving its previous 3PL, and we mapped everything before the trucks arrived: SKUs, shipping rules and packaging standards, loaded from Found's own exports. When the pallets landed, every unit was scanned straight to the shelf, and we connected and tested the store the same weekend. Found was fully onboarded and shipping in one weekend. After go-live, you work with an account manager assigned to your brand, with the people who run the warehouse behind them, and a weekly review of order flow, SLA and inventory. The whole service is on the 3PL page.

Questions founders ask about 3PL onboarding