what day is Cd1?

So I tried finding this but no one really answer what I specifically need. I am taking clomid day 3-7, but I need to know what day is cd1. I started my period yesterday after 5, with medium bleeding, not spotting I was actually bleeding and had to wear a tampon. And then today was my first full day of bleeding. So do I count yesterday as cd1 or today? Also, when I start clomid should I take it in the morning or at night? When are you taking it?