I'd wait till your GT hit 4" or so as they are really slow growers. Probably don't want your GT to be over run by the other fish when it catches up to him/her in size, so my thinking is to give the GT a "head start" on the next tankmate
Then I'd go with a smaller cichlid like the FM's mentioned. Wouldn't add more than one other cichlid though.
Tiger barbs have worked well for me in the past too, to help bring them (cichlids) out of their hideouts more
thanks for all the feedback everyone!ill probably wait a while then add either a fm or a con. sorry it took so long to reply, had classes..thanks again!