I got my peak fertility in the afternoon but not in the early morning

Has this happened to anyone else? I started testing with my ClearblueAdvanced Digital opk since CD 9. Have been getting flashing smileys for 8 straight days (including today). I follow the opk instructions and use First Morning urine to test.

Today, CD 18, after reading an online article that suggests it's best to test between 10 am and 2 pm on opk to not miss the initial LH surge that detects peak fertility, I took another test around 1:30 pm and sure enough I got my static smiley (peak). So glad I did to improve our chances to conceive this month!!

Has this happened to anyone else? Should I test in the afternoons in future months?