With opk’s, never use FMU (unless instructed in the instructions). Choose two times between 10 AM and 8 PM that you can test at every day at the SAME two times (so you don’t miss your surge); and use a 4 hour pee hold each time (and try not to drink a lot of liquids during the hold times). Once the test line is as dark as, or darker than, the control line - you have a positive/peak. Once you get a positive/peak opk, ovulation will occur within 12-36 hours; and the egg - once released - will be viable for 12-24 hours. However, note: opk’s only detect your LH surge. You would also have to temp to confirm if/when ovulation has taken place.