My husband and I are in our 2 month of ttc. Last month I had a positive opk, was clearly unsuccessful in getting pregnant then. Well this week is marked as my fertile week with peak day being tomorrow. I've been doing my opk testing like I should, but I haven't seen any change in color. My question is should I see a slow change in color or an all of a sudden darkening tomorrow? Will be bummed if I don't ovulate this month....