I had a four anchor rotator cuff repair of my right shoulder in October 2013. I believe morphine was what I had, and it definitely helps, as the pain is intense(to tears). I would think PT is essential; I've met people who said they had torn rotator cuffs and never had surgery but I don't think they gained full use, which you should, mostly, if you follow the PT.
I'm not sure about the guitar, I think I went from October to at least December, probably. I think it was March of 2014 I found my Guild JF 30 so I was better enough to play by then but I don't think I was at the end of December. I do remember managing to wedge the guitar(arch backed D25) between my arm and my chest so I could try to do a little something but it took a while to be up to really playing .
Now that I'm almost 70, 10 years later, I frequently have a little bit of ache in my shoulder, but nowhere near as bad as the psoriatic arthritis in my fingers.
I hope you're healing goes well, and be faithful with your PT; you'll thank yourself for it later.