My case was complicated by the fact that I had my spleen removed around the same time. (and due to the same incident)

The pain was my guide. Basically, I allowed myself to do anything that hurt less than x, where x is some quantity of pain that seemed safe.

It was 6 weeks before I got back on the bike. I wasn't able to do any training during that 6 weeks as I was barely able to walk for most of it. (that was the spleen, not the collarbone) After that, I mostly didn't do any structured training, just easy riding. I avoided sprinting or otherwise putting pressure on the shoulder for a few weeks. It took about 4 months (from the injury) for the pain to go away completely, by which time I was riding as normal, minus the drop in fitness of sitting on a bed and couch for 6 weeks, which was actually less than I would have thought. After that, my shoulder worked exactly as before. Same range of motion, no pain. I just have an Awesome lump where the bone fragments joined together at a goofy angle.

You may be able to do something in the intervening period, like ride a trainer sitting up. My spleen situation prevented me from doing that. You'll be back in form with plenty of riding weather left in the season. I timed mine perfectly after the season in early November, so it was late December when I started riding again.