I had my knees done in 2006 & 2008. At the time, I lived in a condo with a private entrance and 14 stair steps up to my unit. 7 stairs up and then a left turn and another 7 stairs. Before they let me leave the hospital, they made me prove I could climb those 14 steps. I did it at 3.5 days, which was when they usually dismissed patients.
For me, the pain was on bending, not weight bearing, so I could do the stairs, albeit a bit slowly. Also, I got cabin fever and drove at a little over two weeks, although that is not exactly recommended.
What you WILL need, most importantly, is to be able to prop your leg up several hours per day to cut down on swelling. Preferably, you will want to raise your leg higher than your body so fluids can drain. Another problem is kneeling. They cut nerves while replacing your knees, so it feels really weird and dead for years. It will also hurt to kneel in the first few weeks, so you will need to find other ways to do things that require kneeling. Even better, find someone else to do the kneeling for you.