How to calculate Day 5 of my cycle, for GP Blood Tests.

[Oblomov]

My GP has asked me to have some blood tests done. On day 5 of my cycle. My period has just started, tonight.
BUT when checking on google, some say that Day 1 is the first day of bleeding, even if it is light spotting.
Some say that Day 1 is the day that you have full flow red blood, so spotting before does not count.
So what am I to believe? Does today count as Day 1 or do I wait till I have full flow and then count 5 days from then?
Either way, it looks like I need a blood test on roughly Christmas Day. So its not really going to happen, is it? Shall I leave it another month?

bump

Right. Thank you very much Fringe.

My first post, as I've had a few of these date-specific tests. I've always been told that day 1 must be full flow, and in fact that if it starts late in the day you count the following day as day 1. Hope that's right!

See now this has confused me. Because Claire is saying mid flow ( thanks for the first post, you will atleast remember what your first post was about , ha ha)

Sorry, been out all day. I wouldn't say mid flow so much, just that you have to have full flow. I often get a day or two of brown/red spotting before full flow and would never count day 1 at that stage. Enjoying TMI in my first NBA thread!

Bloody predictive text, should say MN thread!