When to start counting AF and CDs?

shelli

Hi ladies,

Last night AF arrived but I'm not sure whether I should count yesterday as CD1 or today. Yesterday I had dark spotting and I put in a tampon at night, which this morning was pretty full. So do I count those night time hours as today or yesterday? The reason I need to know is that I have to get blood tests done on CD 3, but do I go tomorrow or the day after?

Thanks!