Confirming receipt releases the escrow to the vendor. Do it only after the package has arrived and you have checked it. Confirming before delivery, finalising early, hands the money over and removes any path to a refund if the item never comes.
If you simply do nothing, the order auto-finalises after a set window, which exists so vendors are not left waiting on absent buyers. That window is not a reason to confirm early. Let it run if you are still waiting on a package that is within its shipping time.
Confirm on your terms, after delivery, never before.