Yes, there is quite a variety - from people who have gone home the night of surgery to people who have gone to rehab for 2 weeks. I think it just depends on how you do, any other medical conditions, how much help you have at home, etc. The average or typical (if there is one) would seem to be 4 days in hospital and then home or 2-3 days in rehab. I know my surgeon is planning on sending me home after 4 days (for bilateral). At first I thought it would be a good idea to go to rehab but now I'm leaning the other way because I know I'll sleep better at home and local rehab facilities don't have private rooms. As long as I can get myself to the bathroom and there are no other problems, I'd rather be at home. However, others have been glad they went to rehab. Some have had great experiences, some not so much. You should discuss it with your OS and find out what rehab center if that's the plan and find out all you can.
Don't listen to the scare stories! For some reason, people either want to tell you how "Uncle Stan" was hiking mountains after 2 weeks or they want to tell you about "Aunt Susie's" horrible experience. Just close your ears to all that. You'll get a much better idea of how it is for folks by reading thru the recovery threads on here. About bilateral, the same thing - it's either the best idea or the worst. Just ignore.
When I was previously scheduled for my BTKR in Oct (which ended up being postponed), they had scheduled me for outpatient PT the day after coming home. When I protested that I thought that was a little soon to be getting dressed and in-out of car twice, I was brushed off with "Oh, it'll be good for you." The more I've thought about that, the more I'm determined not to let them push me that way. I'm going to tell them I don't have transportation for the first 2 weeks so they'll have to send PT to my home. From there, I'll see how I'm doing, but I'm more and more convinced that healing needs to come before "working" at PT which is pushed so hard here in this country but not in others.