Ovulation test

The last couple of days, cycle day 12-16, I've been testing once a day around the same time everyday and it seems like the second line is staying the same..from cycle day 12 to 13 it got a little darker but other than that's it's been roughly the same...how long before I get a positive? How long did you test before you got your positive? Since its faint, should we BD anyways? Thanks for the help!