Opk positive? Confused

So I have a 30 day cycle and ive just started testing with these opks. First one is from CD 17 around 6.30pm second is CD 19 10am and last one is CD 19 9.30pm. I am so confused and I don’t know when I actually ovulate? I bd when I got the second opk result and will again tomorrow morning. Will that cover the window?