Right before you open the windows at night, turn on the whole house fan (maybe 9 PM this time of year in my area). It will increase suction so more cool air comes in through your windows and out through your attic. Turn it off (and close the slats, if you can) in the morning when you shut the house back up. if I stayed home all day I'd probably not close up windows until 10 AM, but I don't think the nest programmability is very helpful for a whole house fan, as you have to close the windows as well. If you try to close the windows with the fan on, I've seen old windows actually bounce back up because of the pressure differential.
They are AMAZING. If it's powerful, you may end up having to weight papers/curtains/etc to keep them from going crazy.