That sounds normal for a cat needing an anaesthetic - the way it works at my vets, you drop them off before consults start, sign the form, have them weighed etc, then after all the consults are done, they do anything that needs anaesthetics, then they have time to come round and eat before the vet will allow them to come home - when Tiger was up the ohter week, if the sedation had worked, I could have had her home at 2ish, but as she needed an anaesthetic and was wobbly when she came round, I had to wait till 4 before the vet would allow her to come home. As I work 9-5 normally, all mine normally have to wait till 5.30, the last couple have been lucky that I was off so could pick them up earlier. You are normally allowed to feed them until anytime between 6 and 9 in the evening though, my vets say 8pm.