I had an operation on my knee in December, I was on crutches for 7 weeks but after 9 weeks I was back on a static bike, 12 weeks on and I was out riding. my knee feels great now and I’m managing at least 2 rides a week.
Best advice I can give is to get to the physio as soon as possible, do as you’re told!
I had torn meniscus and a part of the cartilage had detached from the bone so it was painful to walk on, basically they went in keyhole, tidied up the cartilage and where the cartilage had detached they cut it away from the bone and drilled the bone in 8 places to make it bleed and scab over inside the joint! that’s why I wasn’t allowed to weight bare for so long.
It did my head in not being able to ride but now I’m loving it, it’s still painful to walk but riding isn’t a problem, tbh I hate walking anyway so I’m not that bothered!
Good luck with the recovery!