A positive opk is when the test line is as dark or darker than the control line whichever comes first. After your first positive opk you should ovulate within 12 to 48 hours. So if your first positive opk was the 10th you could have ovulated the 11th or the 12th. Opks don't confirm ovulation though they just test for the LH surge that should trigger ovulation. The number for LH on the app are just a guess and aren't accurate you have to go by the lines.