Hihi, I'm looking for this answer too, as my temps don't really seem to tell me much if I have ovulated. On Wednesday, my temp first registered a spike, then after 15 mins it dropped so I locked the lower temp into my FF chart. Then later in the day, I tested OPK but nil. Second OPK test in the night showed a positive (on 2 different brands). So I was wondering if I could have possibly ovulated before & yet OPK still showed positive.
After the positive OPK, I stopped OPK testing but carried on taking my temps. Still full of ups & downs & FF now declares I've ovulated on Wednesday night itself - 4 hours after the 1st positive OPK. Just seems very lightning quick to me!