Which day is day 1?

Sarah • 3 pregnancy loses. 4 failed IUIs, IVF with 1 failed frozen transfer and finally have our healthy boy!! Momma of a 3 year old, angel twins 10/19, and successful fresh IVF is giving us boy two in November!
Sorry for the TMI! I am starting Clomid this week... Cycle day 5-9 and I need bloodwork on day 3.  Well, I was bleeding yesterday.. Red blood, couple of clots, changed my sanitary a couple of times but it was anything really heavy until about 10pm. Today, I am definitely bleeding heavier. I don't know which to count as day 1!? I'm thinking yesterday? But I don't know and I don't want to mess this up. Please help! I am going to ring my doctor today but I'm not entirely positive it they are open. Thanks for your help! 

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