Twilight's Sparkly Sleepover Surprise now has a listing over on Amazon, complete with a cover and specific information:
Release Date: May 17, 2016
Synopsis: Another fun chapter book for fans of My Little Pony Equestria Girls!
I'm sure we will see previews and expanded synopsis as the date comes closer. For now, you can pre-order it over here if you want to roll the dice.
Thanks to Raul for sending it.