Preschool question

My son starts preschool and I meet his teachers next week. We just moved school districts but he’s been in “school” since he was 3 months old because he was a preemie. He has a pretty significant speech delay and he’s doing better but we’re running into a problem with potty training where he will use the potty if we tell him to but will not tell us if he has to go. He has an iep for school and starts in 2 weeks. My question is how will they handle this and will kids make fun of him for not being potty trained.