J.,
My experience has been that whatever you hear from your doctor is whatever the popular consensus was at the time your doctor went to medical school. So depending on the doctor, expect them to say somewhere between 1-4 periods down the road.
I had a very conservative doctor with my DNC and she said wait 3 months. We ended up getting pregnant in two months and she put me on restriction for my first trimester. No lifting, exercise, traveling over 30 minutes, or sex. Pregnancy turned out just fine.
One thing to note is that right after a miscarriage you are more likely to release multiple eggs. According to early blood tests, my pregnancy post DNC probably started out as twins, but by the 20 week ultrasound there was one healthy baby in there.
It could have been my genetic disposition, (twins run in my family,) my age, my multiple pregnancies that triggered this, but it could also have been that I didn't wait a long time after the miscarriage. My last pregnancy also started off as twins and the same thing happened, but I hadn't had a miscarriage right beforehand. And 1 out of 8 people you meet on the street were conceived as a twin but 1 in 45 were born a twin. So even if it does happen, it is REALLY common and nothing to worry about. Most people just don't realize it because the twin is gone before any real testing gets done.
You will probably be just fine to try again after one period.
Good luck,
S.