I had a miscarriage 5 weeks ago, when will I start my period?

Soon. It's possible to ovulate as early as 2 weeks of a miscarriage. Your menstrual cycle therefore can be within a month. It's important to use barrier methods until you initiate a birth control method to avoid a quick pregnancy before you're ready. Talk to your doc to discuss the best birth control for you and best of luck with your future pregnancies.