I had hip surgery, not shoulder, but I would strongly support what others have said about getting advice from the surgeon. Mine was very clear about how long it would take before I could drive, have full movement, etc. A lot depends on the type of surgery and the physical therapy routine after, but it also depends on the person's general fitness as to how quickly they recover.

And an aside to GoingAway and chococat, the OP's friend injured himself skiing, but CNS (or even SYD, in April) would not be a ski trip.