This is probably going to come off wrong so I apologize in advance if it seems mean or rude. But school is going to suck. Even without a stutter school sucks and it’s a very confusing time. My advice would be to support him. And make sure he knows that there are tons of different support systems to take advantage of. Kids will tease him his friends will tease him. But after highschool nobody will care. Most people are nice about it.