Help!

Ok so I’m new to TTC and all of these acronyms😩 If someone would help me out to get me started, I would SO appreciate it😭

I just purchased my first opk!! Super excited but not sure when to start using them. I have SUPER irregular periods, so I want to see when I ovulate. My cycles average 39-45 days. I’m currently on cycle day 10 (period just ended 2 days ago). When should I start using the tests?