Gilly, there are so many divergent views on what is good vs not good in the PT/activity department. I skew very strongly toward the rest and go easy side, and so I caution that you move in that direction very....cautiously. That said, I did do PT from the get-go with both my surgeries, and at two weeks in, every PT session started with 10 minutes on the Nu-Step. I kept resistance minimal, and I set no speed records. It was comfortable and I grew very fond of that particular piece of equipment.
So the secret here is to hop on for a very brief minute or two. Then hop off and give it a rest. Later in the day try another minute or two. If you're still feeling fine, then maybe try three minutes at a time, over three periods the next day. Now here's where you'll start to think this is no problem, so you tackle 15 minutes on the third morning and half an hour in the afternoon. NOPE...mistake. Just keep increasing in very small amounts. Generally it's better to do small bouts of activity sporadically throughout the day instead of one large burst. The idea is to make sure that if at some point it is too much for your recovering soft tissue, it will only be a little bit too much, and a day or two of rest will easily put you right. Go for the BIG OVERDONE IT, and you may have a nasty tendonitis to deal with instead.
And as you progress, balance that with your other activities. If you're getting outside for longer and longer walks (again, build up gradually) you don't need long biking on the same day. Look at your total activity level as you feel better and better. Listen carefully to what your body tells you....pay attention to little twinges so they don't become big painful aches.
Sharon