I had my first period 33 days 4.5 weeks )after the m.c. I usually have a 26 day cycle though.
I think most people get their first period within 6 - 8 weeks at most.
I wanted to get my period right away so that I could try again ASAP, but the advice is to wait for 3 periods before trying. This is exactly what I did and I caught in the first cycle that I tried. Unfortunately as the second pregnancy was Ectopic I so did not know this until much later on.
I know waiting seems like a nightmare, but in the grand scheme of things it is probably for the best. What I plan on doing in my next wait ( I've decided on a six month breather this time) is to take to charting with a passion. That way when I am ready to start I will be fully armed with all the knowledge I could possibly need as to what happened when, that way the element of doubt will be reduced in my mind. Both pregnancies I have been certain of my LMP, but the consultants have always pulled the " oh but you may ovulate late in your cycle and not be as far along as you think" routine on me. I aim to be fully prepared for that next time. And there will be a next time, for both of us.
I'm sorry to hear of your loss.
Take care of yourself