Please tell me when I should BD!

Emma • married November 2015, TTC since December 2015.
The top test was yesterday's and the bottom was today. I am only on CD 8! I feel like today is significantly darker than yesterday's test which makes me think I'm going to O early this month. I would just have sex as normal, but we are trying preseed this month and I don't want to waste it/or the applicators by using it too early. Advice? Opinions? Please help! TTC makes me crazy 😭😬