It depends on the child. I started leaving for 5 seconds to run and get a towel around 2 1/2. I started letting them hang out in the tub and just checking in on them every couple minutes around 3 1/2. At 4 1/2 I still wash their hair and bodies, and run the bathwater, but they are left alone for up to 3 minutes at a time.
Baths by themselves at this rate probably won't happen until close to 6, since they have little interest in cleaning themselves, and just want to play.
at 7:32 PM on Jan. 1, 2011