Question about ovulation tests and the day of ovulation?

I have been taking an ovulation test every day for about 3 weeks now. (the strip kind) How do I know what day I will ovulate? Until today, I have not seen a line at all. Today was the first day I have seen one. Does that mean Im ovulating today or that I will in the next couple days? I also BD this morning after I saw the line. Could it have happened this morning?