Emission of particles is starting before it should

I have no idea why, but it’s working now.

I am doing a tutorial here: https://www.youtube.com/watch?v=3dTcz5wWvVE&list=UUG8AxMVa6eutIGxrdnDxWpQ I’m at the start of setting up the particle system, and already I am having a problem. The particles are emitting earlier than what I set it to emit. I want the particles to emit when the sphere hits the building section (like is shown in the tutorial). The rest of the building is hidden (h). Can someone tell me what I am doing wrong?


Blend file: http://www.pasteall.org/blend/32005
(I deleted the other buildings and the background hdr image to make the blend file smaller)