Heidi and I have never used OPK's, but we were using a software program called ovulation calendar. We first used it to help not get PG then we used to get PG. Based on Heidi's schedule, we the software program would tell us when we should try (about the week leading to Ovulation). We would BD fairly often during that week, but would make sure we BD'ed the day before, day of and day after ovulation. Worked for us. So I would agree with Beccas and if you know when your O should be then go have some fun and see what happens.