CD1 or CD2?

Miranda • 28. Dental assistant. Barbershop Owner. (🌈) Baby #1. CP 5w0d 3/4/16 & 4w6d 11/13/16
So after 2 months of waiting, AF finally showed up. However, I don't know what to count as CD1. Yesterday, I was cramping all day  and had verrrrry light spotting at night. Today, all symptoms the same just more AF. So do I count yesterday or today? *ive never had this issue before as my cycles had obvious begin and end dates*