Plan on finding something to move into in the next few weeks. Short sales can turn around in a matter of a week if the buyer has all of his/her financial ducks in a row. (That happend to a relative of mine who had to short sale)
The move-in date of course is up to the buyer and seller. But because winter IS coming, you can bet the buyer will WANT to move within a month of purchasing the home if they don't have any entanglements such as their current home hasn't sold yet (in this market unlikely but..), or aren't planning on renting it out themselves.
So, considering short sales are done when someone is up sh%& creek financially and trying to get from under mortgage debt before they're ruined, you can pretty much safely conclude, your landlord is going to jump on any viable offer he gets and agree to their wishes and desires to get the job done....NOT yours. Even with a lease, leases can be broken.
I hope you find something in your current neighborhood for the sake of your daughter. Sorry this is happening.