@drtbkj:

Has anyone tried lately to join “on the taxiway” (ie: at 4 minutes) and TGP was warmed up? I seem to remember jumping in one night to test HOTAS set up and that was the case. If so, I wonder why it would work one way and not at 16 minutes from startup?

Someone already covered this but yes the sim will have the TGP ready to go from taxi or runway selections.