Hi Kelly!!!
My family absolutely adores Fantasmic!! It is a must see on every Walt Disney World Vacation!!!
Good news!!!! According to the official
Disney's Hollywood Studios Calendar on the Walt Disney World Website, it shows that Fantasmic will be performed at 7:30pm on Wednesday, March 7th.
Your 5:30pm Advance Dining Reservation at the Sci-Fi Dine-In Theater should provide you with enough time to eat and then walk over to the Hollywood Hills Amphitheater for the 7:30pm Fantasmic show.
The only recommendation I would make it is to possibly try to slide your reservation back to 5:00pm, if possible. This would allow you ample time to eat and then head over for the show. As with each Fantasmic show, I recommend getting to the theater at least 45 minutes prior to showtime.
I hope that you have a magical trip!!
Scott