New to OPKs...how exciting!

I would say that if your cycles are 24 to 25 days long, and you're supposed to O around 14 days before AF, so I would start using them around CD 7 or 8 so you should get a few negs and then around day 10 you will probably be getting a +opk, and the packs usually say you should O within 48 hours of your first + opk, but in most cases the sperm should ALREADY be there waiting when you O...so make sure you start BDing around CD 7 or 8 also to try to have a better shot at getting that eggie...then on and after O for a day or two if you can manage. That's what's supposed to be the best chances for conceiving, from what I have read and heard. GOOD LUCK!!!