So this is my second month using OPKs. I have been tracking my cycles for over 7 years and used to do natural family planning before we had my daughter, then had an IUD after her. Last month I started the OPKs on cycle day 11 and got my surge the day I expected CD15 even though glow predicted CD14... I have a 29 day cycle and I'm one of those "SUPER" regular girls. Anyhow this month I decided to start the OPKs early beginning on Cycle day 8... Well today CD 12 I got this result. I don't even have the normal ovulation symptoms I do...(sore boobs, little cramps). I would have expected to ovulate later... And even glow predicted the 13th. But it just goes to show you that even super regular people can have unusual cycles and your body just does whatever it feels like. If you aren't using OPKs I reccommend them because it takes put so much of the guess work and I probably would have missed my best day (conception wise) if I was relying on just data even though I have tracked myself for ages and already know what's "normal" for me. I hope this helps anyone who is new to TTC or unsure of OPKs.