What's Really Day 1?

Hi ladies, it's officially not my month ;( Aunt Flo arrived and I am official starting my first bbt charting cycle. Here is my question. On my expected CD1, Wednesday there was blood on the tissue when I wiped and a small spot in my panties but nothing on the pad over night. On Thursday, there was a little bit of dark blood on my pad but fairly light. Today I am flowing with bright red blood and cramping. So my question is when do I consider CD1 - first sign on Wednesday, Thursday in between or flowing Friday?