You can start exercising right now - kegel kegel kegel. Any other kind of exercise is going to put additional strain on pelvic floor muscles that are trying to heal. Those muscles hold your uterus and bladder up, but they aren't up to a lot of work right now. There are ligaments that also help hold your uterus and bladder up, but remember ligaments don't stretch. High impact activity - unless it's upside down - is going to increase gravity's pull and possible tear one of those ligaments. Once those ligaments are torn, the job "falls" to the pelvic floor muscles. And if they aren't up to it, then things fall even further.
Just google "uterine prolapse" for more info. There's a lot more information now than there was when I had mine 8 years ago