Dammit, answer was staring me in the face.
#WC007 02 15:42 03/12/19 should have been
#WC 007 02 15:42 03/12/19
That pops you into the "Ready for synchro" screen, so you then send "#WC 008 01" to activate it.
I still don't know why "#!T" can't be used, as that would be a nice way to verify the time in the unit.