Ovulation kits

I have never used ovulation kits so I am not sure if i understand the instructions correctly. Do you start having sex once the ovulation stick clearly shows LH surge or do you start earlier? It looks like the surge was on CD 17 th. There were some lines showing high LH before that. Only had sex on the surge day and the day after so now I am worrying that I should have started earlier during the days I still had some lines showing. I thought by “positive” it is meant only when you get LH surge and the two lines are equally dark or the test line is darker than the control line.