D.F.
My daughter held out until after her third b-day too. She knew how to go at 18 mos. She used to even remove her diaper when wet, because she didn't like it, and bring me a fresh one. One day I refused to change her pee diapers, I told her to put them on herself. I also told her I knew she was a big girl and would like to treat her like one, which means big girl panties and the potty. i told her if she wanted to act like a baby she could change herself, since she already knew how. Within a week she was not wearing diapers.