Shoulders, even when rehabbed aggressively, take a long time to come back to a good functional state. At about 3 months, you'll have some scar tissue laid down to where you can have some reasonable assurance that you're not going to rip something apart, but it's still not going to be very strong. If you truly want to see just how fast a shoulder can be rehabbed, look up some baseball pitchers that have had shoulder surgery and see just how long it took them to get back into the rotation. Then shave off a few months because you probably won't need to have that much strength with that much Range of Motion, though you will need full strength in a certain ROM necessary for field work, and that ROM also needs to be pain free without meds.
The place to start is to call an PT/ATC that works with baseball players. Then you will likely need a referral to use that provider and here's the key thing: you have to be willing to do all the "homework" that the PT/ATC prescribes for you. If you don't, your recovery rate will be much slower.
A lot of the result depends upon how well you can get the scar tissue to remodel itself along the lines of stress as that will give you the strongest possible outcome given that scar tissue is NOT as strong as the tissue it's replacing. That remodeling requires that you do your part too.
The reason I suggest a PT/ATC is that their ATC background is what provides them the experience necessary to be more aggressive in rehabbing occupational athletes (as much as ambulance folks are, anyway) for return to that work than the typical PT.