So I use the clear blue advanced OPK. No matter when I start to take the test (CD 7, 8 ,9), I get a open circle day 1, and a flashy face on day 2. The estrogen part is not effective for everyone. The disturbing part is the insert says stop testing after 9 days of flashing! WRONG! You can still get a peak. I started flashing on CD 8, I usually ovululate on day 16 or 17. I am on day 20 now and finally got my peak! If I had quit, I would have missed it. 12 days of flashing before my peak came. I would stick to the regular clear blue from now on. Flashy faces suck!