The schedules for parades, fireworks, and major shows such as Illuminations and Fantasmic are imbedded in the park calendars. You'll find the Disney's Hollywood Studios calendar
HERE,
to get the other calendars, click the "view all parks" button at the
top of the page. Once you're at the monthly calendar, click on the
dates in each calendar box and you'll be taken to the daily listing of
parade, fireworks, and show times.
To answer your specific question, during the dates of your trip, Fantasmic will be shown on Sunday, April 26 and Wednesday, April 29, 2009, both nights at 8:30.
Have a great visit to WDW!