Would you like to look at photos of ovulation tests?

Correction, didn't clean up on Saturday

You start from the shortest cycle.
Then you most likely have 14 days before your first day of menstruation for your ovulation.
Your period follows 98% of the time 14 days after ovulation.
Then you start ovulation testing 4 days earlier, so on day 10 after the first day of your period.
Your ovulation tests will increase in clarity. Once it increases, test 2-3 times a day to see if it becomes clearer. Once you're at your peak, your egg can release within 12-36 hours. After that, the clarity on the tests will also decrease.

Regarding your longest cycle, you need to keep testing until day 25 after the first day of your period.
But once you see that your ovulation tests are decreasing, you can stop testing earlier. And you know by the thicker line when you roughly had your ovulation. Then you also know your needs.

Hopefully, it's clear?