I think you need to let your knee calm down, so it's not inflamed before your surgery.
Why not do a few exercises one day and walk on another day? In other words, alternate the days.
At the moment, there's no point in measuring your ROM. Take one reading as a potential end-target for your next recovery and then forget about ROM until you have your new knee. In fact, forget about PT, particularly any exercises that hurt. At this point, they're counter-productive.
You main need now is to go into surgery in December with a knee that isn't inflamed.