I'm sorry, Pansy, but I believe your surgeon is not giving you the best advice. Your knee is angry and swollen. That is proven by how bad you feel after "doing a lot of walking." Please don't do this to yourself. The more you force and push on a swollen knee, the more likely you are to increase your pain and swelling.
Remember that you know how you feel better than anyone. If you are in a lot of pain after the MUA, the world won't end if you wait a while to go to therapy. While you must do gentle bends and stretches throughout the day following the MUA to keep the joint mobile, you shouldn't be doing a lot of exercise until things calm down. Resting and icing are much more appropriate.
If this advice is counter to what your surgeon is telling you, I can only say it is given here based on the experience of the hundreds of people we see on the forum each year. This is what works for the vast majority of patients and, yes, sometimes it is quite the opposite of what they are being told by their medical team. But it is an approach to recovery that is supported by a great many surgeons. Mine was adamant about it. So are the doctors we have associated with BoneSmart. You will have to make your own decision about what to do. But if you find yourself in a lot of pain, I suggest you try our approach for a week or two and see how it works.
If you do opt to go with the more gentle bending and stretching, it is critical that you not allow yourself to over do the other activity in your life. That means no house chores, no errands, no social outings....primarily resting, icing and elevating for at least 2-3 weeks. And definitely no going back to work until things improve.