I never got put in speech therapy. But I stuttered from before school age. You are never going stop kids being kids. He's going to be made fun of at some point. Every kid is. The stutter is just an easy reason. My best advice is create situations for different friends groups. Do outside of school sports or martial arts to be build independent social groups. As he gets older he'll find his circle. By the time I was in late high school no one cared I stuttered any more and my friends would be the first ones to jump to my defence if anyone said anything. What I never had that I wish I did and I've seen recommended buy speech therapists is, make home a place where he doesn't have to be self conscious about his stutter. Make it a non issue at home. He needs a place where he isn't made aware of it every day. My family never got off my case about my stutter despite doing nothing to help me. I'm almost 40 now and more successful in life than my parents ever were and I still stutter the most around my dad because I was constantly made aware I had a fault.