Chalk it up to a minor advantage of being older, but two months before GCS in January, I had had a colonoscopy where they knocked me out with one of the two anesthetics I was going to have for the GCS. It was a risk, but people die during normal sleep anyway, and it gave me the experience of the pre-op prep routine of cleaning out the plumbing. I did not like it either time, but I am here and writing this. I am not suggesting your doctor order you a colonoscopy just for practice, but it could happen, and would be your "dress rehearsal".
I had two anesthetics for the GCS, one for general sleep (both the GCS and CS) and a spinal epidural for the actual surgery site. I came out of the general sleep one very shortly after they took the one bag off the IV tree. Both times I came out with some wild nightmares, but no problem. For the SRS, the spinal anesthetic required several hours after it was cut off to fully let loose of me which was probably a very good thing, and cut my need for other pain meds for a while. I was on oxygen for the first night, but it was more of just a protocol, and they had it turned down to minimum.
As Not-so Fat Admin did, I experienced something that I suppose could have been depression, but was not really the same, I felt like my body was both grieving and rejoicing all at once, and it did take a good cry to get it out of my system. I have a couple of other friends with the same issue, and while I asked if it was the anesthetic, and the nursing staff checked for me, the answer was simply MAYBE!! At 65 and high risk for Diabetes and high blood pressure, and too fat, I came out OK. I did not have a time problem, it was just like taking a nap, but it was an ouchie one to come out of.