I was 8 dptrigger. I tested every other day at 3dpt and on. Well, I forgot to test at 7dpt, so it could have been out then. But, I tested with FMU every time. I would recommend that. Good luck!
Oh, and I used $ tests. I've been using them all along and it actually helped me learn more about how the test works. You have to wait a full 3 minutes before reading the test. The line never showed up right away. I can't tell you how many $ tests I've thrown away after 1 minute. Now I know to wait!