Tww and Positive Pregnancy After Miscarriage

How long after my expected period should I wait before taking a pregnancy test? Should I take it the day of if it doesn't come or the last day if it doesn't come? Honestly I'm super worried because I had an early miscarriage in May and I am so scared to take a test and it be positive like it was before just to have the same thing happen. I'm terrified actually. I don't want to be afraid. I want to be happy if it's positive. Any one else that has gone through this have any advice?