I think it really took about a month after surgery before I started feeling like myself again.
I had terrible knee pain and sleep apnea pre surgery. I used to wear compression sleeves on both knees, stairs hurt and sometimes my knees would lock and freeze up causing even more pain. I also could not sleep without using a CPAP machine.
As I lost weight both of these conditions disappeared which was a huge benefit of the weight loss! Actually, after the surgery I never used the CPAP again. I was also diabetic pre surgery and that condition resolved itself as I lost weight too.