Hi, Kristy! The fireworks at the Magic Kingdom take place each night, and the time varies with the park closing time. You can check the schedule by visiting
Walt Disney World Theme Park Hours. EPCOT also shows the Illuminations Reflections of Earth firewroks and laser show each evening, usually around 9:00 PM.
The Magic Kingdom fireworks can be seen from many locations. Besides in the park itself, you can see them from the beach at the Polynesian Resort, from the observation deck at the Contemporary Resort, from the dock at the Grand Floridian Resort, and even from some of the restaurants.
Illuminations is best viewed from inside the World Showcase at EPCOT, as much of it takes place at water level. You can see some of it from the Boardwalk area.
I hope you and the girls have an awesome time!