Hi Terry,
The time of the fireworks at the Magic Kingdom often varies depending on the time of year, and the park's operating hours. You can check the park hours online approximately 6 months in advance.
To view the calendar, choose the Discover option at the top of each page of the Disneyworld.com website. When you roll your mouse over the "Discover" link, you'll see a listing of each park appear. Choose the Magic Kingdom from the list. Once you are on the park page, there will be a Calendar link on the left bar.
Once you select the
Calendar link, you'll see the a month display. The month display will show you the daily hours. Clicking on those hours will then display a list of parades, shows and fireworks.
You can repeat this for each park.
Hope this helps with your planning! Have a great trip!