Personally, I wouldn't do it sooner. People have different experiences but esp if you are b/fing I wouldn't. You have relaxin hormone in your body for months after PG. I ran right at 6 weeks with #1 and regretted it. Lots of knee pain.
This time I waited until 4 months (what my trainer who's postnatal certified) recommended, and I had my first run today and it was great. I didn't do what she recommended (a run/walk), I just ran, but it was great because I waited.
But it was easy to wait because I hate running inside/outside in the cold, and it just got warm here.
I'd definitely ask your doctor, and listen to your body. With DD I started running 5 weeks pp. I felt fine, but did have a few episodes where I started bleeding again. If I started bleeding I didn't run for a few days after.
With DS I started running again probably 4-5 weeks pp and felt great. (and actually ran a 1/2 marathon 5 months pp)
I was walking too much and started bleeding again 3 weeks after ds was born. I would wait the 6 weeks personally. It's just not worth it. You can really hit the walking at about 4 weeks pp; it's only a couple of weeks after that. You'll be back to jogging soon enough, those 6 weeks won't kill you.