Unfortunately my cycles are not all that regular. I've kind of been hovering around the 31/32 day range but I've also gone to 35 days and 29 days!!! That's why I think I need to get back to using the OPK.
I went to a local Dollar Store last night and bought 15 of them!!!! Would have gotten more, but I couldn't carry any more. Since I found them so cheap I plan on testing twice a day this month to get the closest reading possible.
A good way to save $ on them is to buy online. Also, Answer makes a 20pk that sells for about $19. That's 2x as many as most brands for about 1/2 the money.
texasangel is right. Just wanted to add that the ovulation tests detect your LH surge, which happens before ovulation (usually 24-48 hours before), so once you get a positive test, that is the ideal time to start having intercourse! A day or two before then can also lead to pregnancy, but of course you can't predict in advance when your surge is going to happen :-) Although, you might see a trend after a few months of using OPKs.
Do you have regular cycles? If so, how long are they?
sperm can live in the body for up to 5 days so you need to have it in there prior to ovulating. make sure that you have had sex several days before ovulation, the day of and the day after just to make sure! the egg live about 12-24 hours.