While the bone should be fully healed in 8 weeks I would not advise drawing your bow before you do a little bit of rehab and stregthen up that shoulder. You might get some lingering soreness for a little while (depending how bad the break was and where the clavicle snapped) due to inflamation of the surrounding tissues when you begin to use the shoulder again. Drawing and shooting a bow puts a lot of strain on the shoulder girdle and the last thing you need is a rotator cuff strain on top of your current problems. Be patient and do your stretches and rehab the shoulder for a couple weeks and you should be fine. Draw a low poundage bow first if you can before going back to yours full steam.......simulating drawing a bow on the universal machines at the gym is a GREAT way to prepare your shoulder.

7-8 weeks of healing (you're a young buck so could be shorter but not much) and 2-3 weeks of stretching, rehab and PT and you will be as good as new. You should be shooting again with no problems in 10 weeks.

Good luck.