Besides, as someone on another thread has pointed out, the sniper seems drawn to the challenges of the police. When they say that the sniper only shoots from near an interstate highway, he kills at Seven Corners. What if the sniper sees the closing of the schools as a challenge? Would he be more likely to target children then?
It does seem to me there must be some intel behind this, though it might not be very specific- such as some general statement about "children" from the sniper.
I don't see anything wrong with a day's delay- we're not set up for this kind of terror. Just arranging to cover all the bus stops near the interstates would be a nightmare.