When did you start BC during your <a href="https://glowing.com/glow-fertility-program">IVF</a> cycle?

I am entering my first <a href="https://glowing.com/glow-fertility-program">IVF</a> cycle and my NP called Thursday to let me know she called in birth control for me and that the <a href="https://glowing.com/glow-fertility-program">IVF</a> coordinator assigned to me would call Friday (yesterday) with instructions. She never called. A google search showed most start BC on first day of their cycle and all signs point to me starting my period today. Should I start my BC today even though I was instructed to? The office is closed until Monday.