Go live
Walk one job end to end before you trust it
Why this step
Prove the whole chain on one product, with no shortcuts: create it, sell it, watch the delivery sit waiting for stock, replenish it, receive part of the purchase order and take the backorder, then deliver what you have and let the rest wait. It takes twenty minutes and it finds every setting you got wrong.
Checkpoint
One product has gone from creation to a partial receipt, a backorder, a partial delivery and its own lines in Moves History — and every figure along the way matched what you expected.