I sat around for three days...not moving the arm at all...at all! If I remember correctly I was told not to remove the sling for 5 days when they said I could take it off long enough to take a shower. The shower may have come after three days...I can't remember the details, it's been such a long time ago. When I finally took the sling off and moved the arm in the shower for the first time, the woman actually washing me in the shower, the noise made in my shoulder when first moved was...impressively gross. Sounded like there was mush in my shoulder.
Seems like somewhere around day seven I went back to the doctor so he could take a look and then rehab started shortly thereafter. You'll have to wear the sling for a month or so. You'll be able to remove it for short periods of time to shower and change clothes, etc. Once you get up and moving and can take the sling on and off...you'll probably be able to put regular shirts on. I found a button up easiest because I didn't have to raise my arm to get a slip on, on. After a couple of weeks or three you'll be able to put a slip on, on.
When they tell you to keep the immobilized...they mean immobilized. You will not want to do much with it anyway. If you even wanted to...you couldn't. That arm will be useless for a while.
When you get to the rehab things will start getting better but it's slooooow. They should tell you to do NOTHING with that arm for a while. They told me about people ripping the surgeons work apart by thinking they could get to doing things too soon. One guy, they said, got bored and went to change the sheets on his bed...when he whipped the sheet out to lay on the bed...rip...re-do.
Make plans to not do much of anything.
Follow doctors and rehab orders to a tee.
Sorry it turned out you have to have the surgery.