L.B.
My son's 2 1/2 and I've used the reward system (and day care). They are very consistent at day care, however, he doesn't go poop there. I haven't had luck with that part yet.
I use a sticker for an honest effort and a balloon for an actual accomplishment. Looks like I'm going to have to come up with something good to get him to poop on the potty.
Good luck!