Hold off on the surgery as long as possible, but not so long that avoiding leg pain causes extra stress on your other knee and hips.
I have two friends, one in his middle 60s the other 71 who had a knee replaced a week apart last spring. The guy in his 60s had dealt with pain for a long time but kept both legs strong with daily skiing in the winter and daily golf in the summer. The older guy had his knee pain start at about the same age as the other, but for the last few years had followed the same activity pattern with about half as much activity because of the pain. The older guy still is working on strengthening eight months later. The other is back skiing.
I know several folks with one or both knees replaced who ski SOFT bumps and powder routinely, but don't generally go out and just ski bumps. These guys, however, are all 20-30 years older than you.