Hello. I'd like to help.
General anesthesia can be achieved through different methods with many different drugs and combinations of drugs.
The shortest recovery would be from using only a gas anesthesic called isofluorane or sevofluorane. These animals would be recovered in a matter of 10 to 15 minutes and be able to move around normally and eat and drink after that. Because recovery is very quick sometimes it can be rough as animals don't have time to awake gently and they may be fearful from pain and no memory of what occured.
We often use a combination of medications (including gas anesthesia and injectable medications) to smooth induction (going under anesthesia) and recovery as well as helping to manage pain during and after the procedure. These animals will awaken in a time span of a half hour to an hour but will be quite groggy and sleep most of the day after the procedure. They won't be able to move around well or eat or drink for several hours.
I know this is a somewhat wide time range as far as an answer but without knowing what particular drugs were used it's very difficult to guide you on an exact recovery time. Recovery time will also be influenced by age of the patient, organ function, body fat percentage and length of the procedure as well as whether body heat was maintained during the procedure or not and if fluids were given.
I hope this answer was helpful as far as allowing you to see why recovery time can be so variable.