This is why as soon as I know I'm going to ovulate I take multiple tests a day. Check this out in less than 24 hrs the changes. Maybe this will help someone else to see why to test multiple times when u think it's coming.  'm happy we bd'd last night and this morning as I leave for Germany tomorrow for a few days. It's the first time I hit the window perfectly when we were both home at the same time since my d and c for a Mmc on 12/1/15 Please I hope this time it works.