My policy states that a child will stay in pull ups until they are asking to use the toilet and have been successfully dry for several weeks.

I had the same thing happen to me a few weeks ago. I simply explained it to the parent that if I took every child to the bathroom every 30 minutes, the only thing I'd be doing is taking kids to the bathroom. I have a general schedule I use and I share that with the parents. before snack, before outside, after outside, after lunch, after snack an hour before home time.

If he can't hold it for more then 20 min then the bladder is mature enough to potty train.