I had a total knee replacement three months ago today and can tell you, with knees you can’t overdo during the rehab.
If you do more than you are told to do, you will have more swelling and that will slow down rehab and knee rehab is so long anyway.
Is best if you have your life lined up where you don’t have to see if you can push it.
Another surprise, other than how long it takes, will be that when you are despairing it will ever get better, one morning things just work, when the day before didn’t, as reported by everyone I talked to that had knee issues, so don’t get discouraged.