One of my DDs ended up PTing this way. She had a persistant diaper rash and the pedi suggested naked time. We'd do an hour here and there (basically until there was an accident, or until I was nervous there would be an accident) and after a month or two, I realized she was having longer periods of dry time. We brought out the potty chair and continued on, super low key, just letting her lead, and she did end up potty training herself. She was around 18 months at the time, and did continue to have accidents for awhile. I wouldn't have chosen to PT so early, but in her case, the diapers were causing major rash problems and naked time was the only thing that worked - so we PT accidentally.
Allison
DD1 11/05
DS 04/08
DD2 11/11