How long to keep new tripod on consistent pain meds post op?

My cat just had surgery last Thursday and my vet told me that I can give him gabapentin as needed for pain, but he is very good at hiding pain so I’m not sure how to tell if he’ll need it or not if I take him off. I’ve been giving gabapentin 50mg to him 3x a day every 8 hours as directed. How long after surgery do most people normally keep consistent meds? I think I’m going to start going down to twice a day and see what happens. They said they gave him a pain blocker injection at the incision site that would last 3 days so i’m assuming that’s worn off.