Why would he need it before he sailed? They communicated via Enigma, didn’t they?
The Brits rolled up the entire German spy net in the UK almost immediately after the declaration of war. Who was going to feed the information Germany?
Most of what did get thru was false information fed thru German spies that were turned. The German Army thought the US Army had scores more combat divisions in theater than we actually had due to counter-espionage activities.
Plus, radio communications with U-Boats were sort of like a film loop because you never knew when the boat you wanted to talk to would actually be on the surface to receive. The point is once you flush Intel down the channels, it gets analyzed, distributed, sent & (maybe) received, the convoy has sailed.