How to start potty training?

My 2 1/2-year-old boy goes to daycare and will not go PP in the potty he holds it and then at naptime he wets in his pull-up…we usually don’t have the problems at home doing this and I was wondering if there’s anything else we can try during school… he still doesn’t tell me when he has to go PP but he has a potty watch and we just take him about every hour…Any suggestions to help him go PP at school would be appreciated