I had an arthroscopy on my right knee a couple of years back, i find after its healed pretty much as far as it will, i still get clicking and movement in the kneecap (this is to be expected and painful at first) but i was told once i felt up to it, light riding is a perfect exercise and good physiotherapy on the knee as it moves and stretches the knee, but is zero impact so very good to do!
Id give it about two weekd before you consider it, just to be on the safe side with your wounds/dressings and such, then just take it really steady, no drop-offs of wheelies, and you should be fine with it, just remember when its cold and or wet, your knee will ache, so factor that into your rides and maybe take a stash of ibuprofen with you on future rides!