My son, around 18 or 19 months told me he wanted to go, got out of the bath, sat on the potty and went...he was also taking his diapers off in the crib...so I started training him.
Toddlers are at least 18 months before their little bodies truely develop the ability to "hold it" so starting now is a great idea. As she grows, get a little more serious about it.
Something no one told me about training is that regression is normal. They can be doing well for weeks, and then all of a sudden just quit going in the potty and having accidents. Just roll with the punches. Follow HER lead. Afterall, it is HER mind and body. I say go for it! At this age, I would only worry about day time training and forego the nap and night training. Not much chance of her being able to hold it all night.
at 9:50 AM on Nov. 13, 2008