Along with my comment below; the other important thing was to be well prepared for any possible accidents that could happen at school. We always had spare pants in a bag. It is so important for children to know that there is a way to manage accidents if they do occur.

It can be a very good idea to have any possible health concerns checked by a GP; which is something we had to to for one of our children. Then it was about managing the issue and we had a sensitive and proactive conversation with the teacher and going forward it all went well.

Another idea is you could leave him a little note in his lunchbox to go to the toilet at break time.
When you don’t see improvement in a while you could take the accidents a bit more serious. Children who wet themselves could actually be constipated and it’s good to keep an eye on that, but for now I would say it’s to early to seek professional advice

Some toilet regression by big changes (or in stressful situations) is very common. Best you can do is to keep working on this transition and show patience and understanding. Personally I wouldn’t give the toilet accidents too much attention or see as problematic but you could have a private chat with the teacher so she can remind him to use the toilet

In prep they are often further away from the toilets than in kindergarten. Totally different place and sounds like he’s just so caught up getting used to all the newness of big school, that he’s disconnecting from his bodily cues. Get him in the habit of doing wees at every break, and definitely talk to the teacher about it. If it happens just in the afternoon, perhaps the teacher needs to send him to the toilet well before the final bell, as there can be a big gap between lunch and hometime..

My friends actually going through something similar with her daughter. Have you had a chat with the teacher? There is usually a reason for it but it is getting to understand that reason. It might even be worth seeing if there is a school councillor your child could see as this could be helpful too.

Have you spoken to the teacher about what is happening. When our son first started school he had accidents every now and then but was always embarrassed to tell anyone. The teacher never knew until we spoke to her. She then kept an eye out and if he ever had accidents she knew there was a change of clothes to change him. He is in prep now and has only had the one accident because he was too afraid to go to the toilet on his own after accidentally locking hi.self in. Speak with the teacher and let them know your concerns