I don't know about every one else, but I only temp once a day. First thing in the morning; at the same time every morning. Its usually a little off on the weekends; I mean who wants to get up at 0530 if you don't have to? And you're looking for a definite thermal shift. You temp will go up the day after you ovulate & stay up until you start your period or get a BFP. Most of us use fertility friend. You can also record the results of your monitor & CM there & its free.
This is my current chart using fertilityfriend.com See how my temp was only 97.33 on cycle day 15 (CD15) then it hops up to 97.87 on CD16? That's what you're looking for. After you have a shift & 3 temps that stay up, fertility friend (FF) will put your O date on there for you (the cross hairs). Sometimes if you've been having issues with temping (skipping days, temping at random times) it won't be perfect. But that's what we're here for! To stalk your chart & give you expert (or not so expert) opinions on what day you O'ed. We all also obsess over the two weeks after O... waiting on the BFP.