I've semi regular cycles, the last 3 cycles were 43, 39, 37 days, 37 being the most recent one. Today is CD 39 of the following cycle(4th). I see this vf line with FMU and it showed up before the 5 min read timeI used these tests in earlier CDs just to see how they work(these tests have been the bad guys lately based on reviews on amazon, giving false positives) but hadn't given me faint lines. Could see them when I squinted and tried really hard and that was way after the 10min max read time.