lol yes it is a bit clinical....

It is best if you can watch your cm, as soon as it changes from ewcm or watery to a creamy consistancy you have Oed and need to count off your 12 hours, so maybe do a practice cycle or 2( 3 is better) and see if you can pin point your O! Not everyone O's 12 hours or 24 hours after the + opk so it is best to find out your own rhythms...