Sorry to hear about a foreign body, and happy to hear its been resolved, far too often they are left too long!
A foreign body in the intestinal tract usually gets to cause pain and discomfort a few days before anyone finds out what it is and gets to deal with it. When removing the object, your vet mast have to remove some damaged intestine along with it, this may prolong recovery and is pretty serious. You would be informed about this. A "normal" removal includes an incision which is stitched up and needs to heal afterwards, this takes some days depending on place and size of the cut. I would not expect anyone to be running around smiling after this! In addition, there has been stress, disease and discomfort/pain before the operation, recuperating from this takes a while. Pain meds usually cause artificial well-being: as is mentioned above, pain slows you down.
In sum, don't expect to get home a cat that climbs trees and catches up on the rats the first week, and also you should be in for a check-up after max three days. Good luck!