I can kneel on both my knees - one almost 6 years old and the other almost 3 years old, but I still don't like the way it feels. I don't think that will ever go away.
However, I'm very glad that I can kneel, if I have to - and get up again.
Last year, when my husband was away, the water filter in the kitchen sprung a leak about one in the morning. I had to go out by torchlight onto our long driveway and lie down on the asphalt, putting my hand down a deep hole, to reach the valve that turns off the water main.
As it was, my kitchen was flooded, but if I hadn't been able to turn off the water main my whole house would have been flooded.
I practiced kneeling by starting first on the bed, then graduated to kneeling on a cushion or pillow on the floor, then finally onto the carpet.
I can kneel on a hard surface, but it feels very uncomfortable and I try not to do it.
Some people never can kneel and some surgeons prefer it if you don't, so it pays to ask your surgeon.