When I had my Mirena removed I wanted to make sure everything was "working" and learn about my body since I hadn't had a period in almost 10 years due to birth control. I don't even remember what my cycles were like way back then. So I started charting my BBT and used OPKs a couple cycles. I've learned my cycle ranges from 26-34 days and my ovulation occurs between CD13 and CD21 with it most commonly being around CD16. I also learned I have a very long LH surge and get several days of dark positive OPKs before ovulation is confirmed by my BBT. This cycle I had four days of OPKs. (The first two are negative, the third is questionable in the pic but definitely positive in person, the remaining three are clearly positive)
https://im1.shutterfly.com/media/47a1cf22b3127ccefed3a012a9f500000030O00EauGTRm0ZNAe3nw4/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/
Last month was three. We've been more ttc for the past five months after ntnp for a few months. This whole thing is driving me crazy though so we're going back to NTNP with more preventing than trying. I'm going to finish charting this cycle since I'm halfway through it but then I'm not going to chart my temps, use OPKs, nada. I will keep track of my CD1s but that's about it. I don't want to count days anymore. And I'm guessing I'll be too busy to ttc until about April of next year anyway. I'm going on two two-week-long business trips over the next five weeks, then we have the holidays, then more week-long business trips every couple weeks through March 2012. It's going to be CRAZY around here!!
Anyway, if you do decide to use OPKs, you can get ICs (internet cheapies) for next to nothing on Amazon.com