I looked around on Google, Allpar, Wikipedia, Hamtramck-Historical, etc and all I could find was that the earliest SPD on the SuperBee Registry is Jan 15. Another clue (maybe) is that some sites say the 4-speeds all had Hurst shifters, which happened on Road Runners & etc sometime in Dec '67-Jan '68 according to guys here with original '68 cars...a few Feb '68 cars still had Inland shifters, so that changeover date apparently differed among the various assembly plants.
Feb 1st dealership memo from Dodge Div clarifies 4-speed standard in SuperBee, doesn't mention shifter. I didn't find any earlier mention of the SuperBee, but somewhere there has to be a memo to the dealers about its introduction.