If your cat is going to have anesthesia, check with your veterinarian for their specific instruction on pre-anesthesia care for YOUR cat.
In general, most cats are permitted to have a normal schedule until the night before. Their last meal is often taken away at least 4 hour prior to the time they are expected at the veterinary hospital.
Some veterinarians prefer food be taken away the night before but cats maintain access to water. Cat that are permitted outside should be kept in the night to ensure they are "there" and ready to go for their appointed time.