Not actually TTC yet (only a few more months to wait, woohoo!) but I've had to change contraception recently and condoms make nervous so I ordered a bulk bag of ICs just for peace of mind.
They arrived this morning and of course I pee'd on one (because I'm a lunatic!). On the stroke of 10 minutes a faint line appeared. So obviously took another (same urine) and the same thing happened.
Held my wee all day and took 2 more. 2 squinter lines both appeared at almost bang on 10 minutes.
Highly sceptical because we've not had unprotected sex this month so to say I felt a bit shocked was an understatement. I only wee'd on it for shits and giggles!
Anyway in my highly sceptical state I decided to dunk one in the sink... Turns out my sink is also pregnant! 
Sure enough I've just started bleeding! Bloody internet cheapies, gah! From now in I will be discarding them after 5 minutes to save myself the horror of evap lines.
The picture is my sinks, albeit very faint, BFP 