Updating my original post from earlier- AF just arrived (2 days early). DO NOT trust evaps!! 
Original post below:  am on 3 days of colored evap lines- will only show up 2+ hours after timeframe. Different brands. I went and bought a digital but I'm afraid to take bc if I really do have 50 hcg, I shouldn't be struggling for a bfp on these... AF due Wednesday, but afraid to be let down since it's also my birthday!