Mesix
Obergruppenführer
I would recommend a GS on turn 72 and plant him as an Academy. This will likely generate moreMayan Long-count forces one to put great people to good use!!
Yeah, I managed to research Theology pretty easily by turn 63 on emperor so got these long count GP @:
72, 86, 101,117,133,152,183, 234
The first two took Admiral and General as suggested...
Then it was Engineer (wonder), Merchant (CS Ally and $$ for settler), Great Artist (to extend Golden Age), Scientist (saving), Prophet (extra faith points).

I generally plant GS up until the Industrial/Modern Era. Somewhere between Public Schools and Research labs, I start saving them for bulbing later.