be patient, and obey doc/pt orders, will pay dividends in the long run.
I'll try to be short. I have had 3 knee ops, none of which were reconstructive like yours sounds, all more minor. 1 micro fracture right knee, results great, 1 micro fracture left knee, results shitty, subsequently 1 meniscus repair (stitches in meniscus so longer rehab) left knee, still recovering but optimistically good.
long and short, I probably jumped the gun on all of them when it comes to getting back in the yak, wish i woulda stayed in the gym longer before the boat.
to paddle easy whitewater and roll? do what doc says, you'll feel ready to sit in a kayak and paddle well before you feel ready to ski, hike, even bike, but don't necessarily do so.
to paddle tough whitewater? you'll still feel ready but the numerous other aspects of running harder stuff are not good for knees at all. i.e.: hike ins/out while shouldering boat, scouting, being prepared to play a safety roll whenever and wherever, aside from safety;r escuing on and off river, self or others, not to mention the inevitable swim.
I had all my ops in winter, kissed away ski season with no qualms, rehabbed religiously, then spring came, knee feeling better, and felt fine in boat. The actual act of sitting and paddling/rolling in boat was probably fine, so i figured, lets get after it and knee will heal better by school of hard knocks. Not sure my knees or knees took any steps back, however i feel in hindsight my time would have been better spent in the gym doing the boring rehab drills and waiting till knee was sufficiently strong to deal with the many obsticals whitewater rivers can throw at you.
I said i'll be short, was not at all, but you do the same with your rehab. hit it hard and listen to the geeks with the doctor degrees. PT will do much more for you post op than any doc will, and don't be too anxious to fire up big drops. even if the flows are high and your itching to get out, hit the gym instead until you're def. ready. I talk like an old grizzled vet, I'm not, still young, but wise enough to be kicking myself in the ass for trying to hike around with a creek boat and run the shit before my joints were properly strong.
Strong is the main word, strong is much different than healed. I think structurally i was healed but not strong, and a weak knee is not a healed knee. do your time and come back to the rio rather than the docs office.
got way long here, back to OP, to run easy ww, you'll prob feel fine before doc says ok, so not the worst thing to get in a pool and roll, but gym will do you much kinder than the river will, till your ready.
My whole ramble in one sentence: listen to your doctors and PT before any idiots (self included) on a boater forum