Both of my children potty trained at 4 and 1/2.

Older son had developmental delays and he just didn't get it and then after that we had holding issues that led to constipation and OH MY GOD it was horrible. He wasn't out of a night time pull up until 8 and it was finally about then that I was able to stop worrying if he had a bm that day or not.

Younger son was just stubborn. Needed to potty train for Pre-K 4 so he did in a week in April while his older brother was at a Spring Break camp and we weren't distracted and was ready to go in August. His night time was about a month later.