What time is it supposed to happen?
It already happened. We were left behind 

That's interesting. I woke up this morning (it is now eight something AM) and my wife is gone. So it looks like the kids and I were left behind.
I get why I was left behind but the kids? And my wife?!
Oh well, guess I might as well go and loot some houses.
Wait... where the hell are the Zombies?! If I was going to get left behind, I was really looking forward to "killing" a few Zombies... And my Aliens?! Damn it!