When is the best time to take a opk and when is the best time for ovulation? Before or after your period...? I am so very confused with all of this ovulation and opks. Because I have very irregular periods and I never know when my period is gonna come or when I'm ovulating. I've been taking clearblue digital opks for 3 days now? 3 days previous from today, including today and all of them were negative. I don't know what to do anymore. I am starting to become discouraged with opks!! And I am taking vitex and evening primrose oil to help regulate me and still no period yet this month either. My last period was February 4th. Please please please help!!!