not an expert, but i did chart for a while. SOME people tend to have temp dips prior to ovulation, not all. You know your body better, so if you think that CD 10 is too soon, then it probably is. Our temps can shift for lots of sleep. If you went to bed earlier or stayed up later than usual. Slept in, got up early, had sleep deprivation the night before, etc. I think that .3 is a small dip - I wouldn't worry, but if you are concerned BD any way to be on the safe side.