What marks the "start" of a miscarriage?

Hello,

So I don't even know if this will matter in a weeks time but I want to know if anyone out there has an answer to this.

I recently had a miscarriage at 6 weeks and they say that when you have one this early that your cycle starts from there, meaning you'll ovulated 2-3 weeks later.

But I can't find any information about what marks the start of that cycle. Is it when the heart stops (there was a faint heart beat), when the bleeding started, when it stopped, when I took the pills, or when the tissue passed?