Which opk should i consider my 1st positive?

Cybel

The 1st being last night around 11:30pm 2nd was at 4:30pm today.

Also which is the better day to BD the day of the Positive opk or the day after (est. ovulation)

UPDATE!!!

So I took another opk today and it is more positive!! Why is it still getting darker? Does this mean that I’m about to ovulate today?? I also feel a lot of ovulation cramps