I just had this surgery (called open release) which severs the transverse carpal ligament. I also had the cubital tunnel surgery (anterior submuscular transposition of the ulnar nerve) at the same time in my elbow which also severs a ligament and the ulnar nerve is repositioned.
It's actually a very simple procedure and is usually done under local anesthesia and a HEAVY sedative. It has worked wonders for my right arm and hand and I will be getting the same surgeries next Wednesday on my left arm. I will finally be relieved from waking up every night with no feeling in my left arm!
As for setting you back, I had to go to my college classes the next day after the surgery. Yes, it was uncomfortable and I couldn't write (I took pictures of board notes), but bypassed the pain meds that morning so I could drive. The pain from the surgery could last 6 months (in the palm from the severed ligament). I had the surgery in February and it literally got better every day. My pain is completely gone now!
Good luck with the surgery. I'll let you know how my second one goes next week!