Potty Help

Do any moms have any tips on how to get my 2 1/2-year-old to tell me he hast to go number two. He started daycare about 2 months ago and he was mostly potty trained. He would poop on the potty before he would even pee, but now he just goes pee and will not poop. The school says he doesn’t do number 2 at school. He communicates very well and I’m thinking school put a rift in his routine and comfortability. I want to find ways to get him to tell me he has to go poop. He has expressed it every now and then but I don’t know how to make it permanent. Also I am concerned because I’m ready to start overnight potty training which I need tips on as well. He started potty training at 1 and a half and has been excellent thus far.