I had the surgery 4 years ago. I tried to do too much rehab and went back to work too soon and actually separated the rib cage to where I had a rubbing noise in my chest when with certain moves. Went back to the surgeon and he scared the living bejeebers out of me - He said that I had to do virtualy noting but eat, sleep, and go to the bathroom for 2 weeks and let the wound heal back up or he would have to go back in and rewire the rib cage back together. I did exactly like he said.
I waited a few weeks after that to start rehabing and now everything is fine.
I have a friend that had this surgery and 7 weeks later rode in a 150 mile MS ride. I was pretty amazed and jealous.
Take it easy, your body has been through a lot. You don't want to chance a fall and prolong your healing time. You'll have lots of time to enjoy riding later.
Best of luck.