Agree with the other girls.
I O generally on CD14. My cycles are generally 28-29days. However, every now and then my cycles are longer and my O date is a couple of days later. I temp and use OPK's.

OPK's are only Positive if the test line is as dark as, or darker then, the control line. It is possible to get lines at any point in your cycle, it is only the really dark ones that count.