My son broke his non-pitching-side clavicle last summer, and I did a fair amount of research on it (to see how irresponsible I was being letting him start football practice three weeks later).
Because your son's break is serious enough to have surgery, the initial recovery may be a bit longer, but the good news is that he will have a well-aligned, well-healed bone. This eliminates the biggest risk, which is a bone that is more susceptible to re-injury because it doesn't set and heal well. The realignment will also maintain the bone geometry of his shoulder. I was a little shocked looking at my son's x-ray with the bone separated and misaligned and the sports docs basically saying "eh, not too bad."
As far as recovery times, the link below gives some information based on a study of NFL players--an average of 8-9 weeks after surgery to return to pro hits. My son played his first football game inside of six weeks with some pain and was pitching (and catching) without much pain or problem in that same time frame. Our doctor was pretty aggressive and I think pushing the range of motion and use exercises from early on helped him shorten his recovery. We've also been pleasantly surprised that the large bump has mostly subsided at this point.
It is of course a little worrisome at the time, but now looking back it seems like no big deal. Good luck to your son.
http://www.deepdyve.com/lp/sag...-national-HcB7pdkksc