Hi Shari, how exciting for your family to be planning a first time Walt Disney World vacation. Even though you still have several months until you leave, I'm glad to hear that you are thinking ahead and planning the details of your trip.
I would recommend planning your days around the Extra Magic Hours. This way, you can get the most out of the days at the parks that have early opening or a later closing. These Extra Magic Hours are only available to guests staying at a Walt Disney World Resort hotel, so this is a prime time to get in some of the more popular rides with fewer crowds and shorter lines. These hours are usually posted about 180 days out, so depending on when your trip is planned for October, you should be able to view these hours fairly soon. To find the hours for each park, click on the "Parks and Tickets" tab at the top of the official Walt Disney World website, then go to "More Park Hours" in the drop down menu.
I, personally, always like to visit Magic Kingdom on my first day. This is the quintessential park, in my opinion, and seeing Cinderella's Castle as you enter the park is a great way to start your magical first trip. In addition, I think for your daughter's age, you would really enjoy going to Magic Kingdom and Disney's Animal Kingdom twice. These happen to be my daughter's favorite parks and she is also 7 years old. Speaking of Disney's Animal Kingdom, your daughter might really enjoy doing
Wilderness Explorers, an interactive activity through the park. It's included in the price of admission. This was my little girl's favorite thing about our summer trip.
Fantasmic! is an amazing nighttime show. However, my kids were a bit frightened by some parts of it, so we haven't done it the last several trips. Although, you could make that judgement based on your daughter's personality.
Have a magical trip!
~Allison L