Cm check

When I did the cm check I did it on June 21 it was sticky cm open and June 22 thick and creamy and open. Does this happen after ovalution? I think I o'd on June 20. I don't do the opk, I've been ttc for over 3 years now and I haven't got into checking temp. or opk. Trying to find a way to determine when I o'd other then opk and temp. Any advice on this should I start temp and using opk? If so is the ones on eBay good to use? Do u take a opk everyday and how many times a day?