I had rotator and labrum surgery on May 8, 2008 and was riding carfefully in late June, so it was about six weeks for me... but I was probably pushing it. If you ride so soon, you may want to adjust your riding position to more upright and be extremely careful about trying to catch yourself in a fall. My PT did know I was riding at that point and sanctioned it with a wag of the finger about taking it very easy. YMMV of course but I'm going to say you should most likely wait at least another month.