You'll find it varies alot. Most suggest waiting for "readiness signs". However, my son got to 3 without showing any readiness signs or interest so I just plowed ahead (that was my pediatrician's advice as well). In 48 hrs, he had the basic idea (for peeing, anyway). Around age 2, we bought a potty and tried to get him to sit. he screamed bloody murder so we punted and tried again a few months later. Around 2.5, we attempted to get him to sit on the potty once a day. If he did, great. If he refused, we just moved on. After a while he'd sit willingly and usually pee. We then started potty training. We went directly to underwear (except at bedtime). We did use pullups for school but they were a problem when we actually wanted to potty train since he'd happily pee/poop in them.
at 6:58 PM on Jan. 3, 2011