Get the signed POD before the truck leaves the receiver's lot.
A signature from the driver is not a delivery. A photo of the building is not a delivery. The receiver signs, and you have that copy in hand before the trailer rolls.
Do not chase it later
If the dock will not sign, the driver calls you while they are still in the door. You call the shipper. You do not tell the driver to leave and that you will get the paperwork tomorrow. Tomorrow the clerk is off and the freight is in dispute.
The POD is part of the delivery. It is not a follow-up task.