No real advice except follow the doctor's orders. If you tear the tear you probably will make it worse and at best have to start over. And don't go crazy eating unhealthy stuff while he is also not able to be active. It's easy to think of it as a vacation but this vacation will last 3 months. You can do a lot of damage to your waistline in those three months. Especially when you are sitting around most of the day.
My mother had both of hers done separately. She was back to normal pretty quick both times. She was in her mid to late 60s at the time. Normal equals out riding her bike, playing tennis and a somewhat physical job (X-Ray Technician)
I had mine done in 2014 or 15. My rotator cuff had torn completely off. Needless to say it took a lot longer than three months to get back to normal. The physical therapist commented how my doctor underlined "massive" twice on the paper work.
I work on a computer so I was back to work as soon as the oxy wore off.
I'm pretty sure my PT started almost immediately. Which, at first, was just them moving my arm around. That was just to keep my shoulder from getting stuck in the socket. I'm sure the machine Magnum mentioned is the same thing, I just payed a human to do it. Then I graduated to doing stuff at home like carefully carrying a couple of dishes and lifting mouse weights. (those 2 pound tiny weights that look like a mouse could bench press them).
The most uncomfortable part was I had to sleep on my back at an angle for the first few days. I"m not sure why, maybe so I wouldn't roll around. Picture sleeping on a reclined reclining chair. You'd think it would be somewhat comfortable but it wasn't!
Here's a picture of the doctor putting a screw in my shoulder. (I don't find it too gross but if you are extra squeamish you might want to pass)