Yes it is hard to hear your doc give you conflicting info---but I attended a Doctor's conference in Miami last year and the hot topic there was that less is more when it comes to exercise in the first month. It is hard for the athletic person to hear, but taking it easy in month one, which allows the soft tissues to heal, your quad to wake up and begin functioning will give you better results. I don't think it is necessary to challenge the doc either, but maybe at the end, you can give him a heads up!!!
One of the things that happens early on (ask me how I know this!) is that you start to feel pretty good while resting, icing and elevating---so, you decide to just run to the grocery store for two things!!! I felt as much pain as I had had the first three days. I could not believe that over doing it would cause that much pain---but, it did!
the basic anatomy issue is that if your quads and hamstrings are not fully functioning and firing, your joint has no support from the muscles when you walk around. It has to support itself. In a few weeks, the quad will be up and running and will help to support the joint. At that time, it is okay to start light exercises since the quad will be able to handle it.
I found that I could ride a bike from the second day, but my PT put the squeeze on me. Five minutes at first. It felt so good, so of course, I pushed to 10 minutes---and my knee screamed at me. I also think the first month does not need much PT. Mine used to give me massage of the leg, some simple table exercises--like leg lifts and clam shells---maybe 5 each in the early days. If you have to pay or have a limited amount of PT appts, it is really a waste to go to PT too early. After the first month, you can begin to work on rebuilding the quads and hamstrings when the soft tissues are healed. keep up the good work!!