Both my boys were fully trained by 3 1/2. I tried earlier but didn't take until 3 1/2 (when they were ready). While I was training my youngest son his pediatrician recommended (last summer) to let him run around outside with no pants, diaper or underwear on. Put him in a long t-shirt and also put a potty outside. I never did this, but thought I'd share with you what his doctor recommended.

And yes I agree you've got to get ride of the pull ups my son did not like wetting his paints (it took a few accidents in his underwear for him to get it).

Good luck!