First and foremost, I tell all parents to tell your child that it's OK to stutter. It would have meant the world to me. But here's the tricky part. Speech therapy tends to give the message that it's not OK to stutter and it needs to be fixed. At your son's age, it's hard for kids to fully understand two different ideas like that. In my experience, speech therapy is only effective when you're more accepting, have confidence, and have a positive view towards communicating. You may want to focus on that part first to give him a solid foundation, and then work on speech therapy. The speech therapist at school should be able to do both parts. Just my two cents. I just read a really good piece about this if you care to dm me. Edit: regarding the second part of therapy, focusing on fluency. Maybe talk to your son about it? Some kids don't want therapy. And you know what? That's OK too. I know to us parents that's scary, but you see many successful people here that stutter. You only need a positive environment.