Fireworks are typically presented on Fri, Sat, and Sun nights before the official start of the holiday season. After the Holiday season starts, they are typically presented nightly (weather permitting).
To see the nightly entertainment schedule, on the disneyland website, under the parks and tickets tab, click on entertainment schedule. You can then navigate to whatever day you want info on up to 6 weeks out.
On the Disneyland calendar you have to look at the Five-Day View or Day View if you want to see the detailed entertainment offerings. If you look at the Month View, it won't list the entertainment (e.g., fireworks, parades, etc.) schedule.
Fantasy in the Sky is the show that is being presented prior to the start of the Holidays. After the Holidays start on the 10th, they switch over to the Holiday fireworks show ("Believe...In Holiday Magic" Fireworks Spectacular).