Before your inventory ships to a 3PL, provide a complete prep specification: SKU list, unit counts per SKU, label type (FNSKU, UPC, custom), packaging requirements, and destination channel for each item.
Make sure supplier cartons are marked with purchase order number, SKU, and quantity per carton. Cartons that arrive with no external markings take significantly longer to process at receiving.
Confirm whether the 3PL needs your FNSKU file or whether they pull it from your Seller Central account. Different prep centers handle this differently — confusion here causes label mismatches.
Share your outbound timeline before inventory arrives. A 3PL that knows you need the work done in 48 hours will prioritize differently than one that assumes it can process within a standard 5-day window.