OPK tests

Sara

Hey guys, I’ve been testing with opk and I was wondering if it gradually gets darker the closer to ovulation you are or if it’s just randomly negative till it’s positive? Mine appear to be gradually getting darker and I’m wondering if that’s normal and if that means I’m ovulating soon? I’m so excited to be on this journey but I don’t want to over think it, but I also don’t want to miss my window!