I tore my miniscus, ACL, and bone bruising in the knee . My surgery was about 3.5 weeks after the injury. Once I could walk (but before my surgery) , I rode an exercise bike as often as I could. I did a bunch of exercises to help with the recovery.
I am about 3.5 weeks past my surgery, and I am still walking with crutches on uneven ground. I can walk short distances around the house without crutches, but my better half (which is a PTA) gets mad. According to my physical therapy plan, I am not supposed to walk without crutches until this Thursday. It is my intent to start riding a stationary bike tomorrow (if swelling stays down). I want to get back to normal ASAP.
If you are interested, send me a PM with your email address. I will email a copy of the physical therapy exercises that you will perform after your surgery. If you start them prior to your surgery, it will aid in your recovery.