CD1??

ClaudiaStar21

I used to post on IF from time to time and on TTTC when I was TTC DS. I have had a diagnosis of PCOS since I was 21. I went back to the RE FRiday to do baseline bloodwork to see how my hormones are after pregnancy and finally weaning DS and to see how my insulin resistance is. She wants me to go for CD21 progesterone testing. I will call and ask her tomorrow but didnt know if anyone had some insight. 
I went to RE on Fri. She did and, internal u/s. I was expecting my period any day. Saturday I had about 15 min of bleeding and today I had spotting. Do I count Sat or today as Cd1 or wait for the first full flow day. What if I get no spotting tomorrow? 
Thanks in advance.