Good luck with the surgery. I broke my collarbone some years back after face-planting off my mountain bike! I am also the veteran of many broken bones. I was lucky that the collarbone displacement didn't require surgery, but if they pin yours, then theoretically you might be able to do some lighter activity a little sooner. The critical thing as, everyone else is saying, is speak to your consultant and follow their advice. Don't jeopardise your recovery by pushing it too soon. In the grand scheme of things the weeks you may be out of action are just the blink of an eye, and you'll return to the bass even more motivated to get playing!