RE: Can I create serial numbers for my items BEFORE I receive them into inventory? Want to create labels for them before they arrive.
Could you just use a custom record for this purpose and a custom HTML/PDF process? Either via Suitelette/xml-pdf process – or a saved search to HTML/PDF?
Pretty custom – but doesn’t have the negative inventory impacts of doing a premature item receipt. (Also – think about the accounting impacts as well)

Do you see any issue with the previously suggested? Create the serial numbers by inventory adjust or “receiving” and then deleting the receipt so that it reverses the change? It seems to function but as we are still in implementation phases, I’m not sure if it has an accounting impact.
Performing an item receipt will generate a hit to accrued purchases (i.e. amount received not billed) depends on your account type, and to your inventory.
Performing an item receipt early could cause someone to have the capability to fulfill something you don’t have in stock. – that’s probably the biggest risk to you. The other piece might impact your financial ratios a touch, but unless you are ordering a substantial amount of product, shouldn’t move the needle all that much.
That said – on reddit it looked like SuiteMike recommended you expose the inventory details column on your PO to see if you could print your labels from there – and I think that’s a pretty good looking idea if it gets you what you need. Better than either answer listed here.

Thanks!