when is CD1 & what to expect w/ chemical

As

On Weds I learned my hcg had gone down to 28 and so I’ve been waiting to miscarry. HcG never really got above 40ish, so it wasn’t too high to begin with.

I started spotting Saturday and some spotting today (Sunday).

Would that make Saturday Cd1? Or do I wait to bleed more ? Will I bleed more or might it just stay spotting since I wasn’t very far along/chemical pregnancy?