I am in a similar situation with the MRI showing a medial meniscal, posterior horn tear and patella chondral damage. The consultant talked about surgery (debride) and I asked about recovery time and he said it varies between individuals but suggested the following
two days bed rest
two weeks of limited activity (no driving etc)
up to six weeks of taking it easy, so easy short rides, physio. strengthening
then its down to how much pain you can tolerate but it may take up to a year for the pain to go
I think the key here is everybody is different, depending on the nature of the original injury, age fitness etc
5 months since the original injury and I am still working with the physio after having had one relapse after I thought I had got on top of it with strengthening exercises.