Below is from the "MAPS: by Robo" Sticky Post always found near the top of this forum.
What a FastPass for Fantasmic! offers is more CHOICE in seating.
If you DO get a F! FastPass, you can choose to sit in either the FP section (virtually the entire left half of the theater) or the Standby section (virtually the entire right half of the theater.)
So, whatever section has the better seating at the time you arrive, you can go there.
Without a FP, you can only choose a seat in the Standby section.
There is a very good chance that you can get a FP+ for F! as a 4th or 5th FP of the day because they issue SO MANY of them (enough to cover nearly the entire left half of the seating.) On many nights, it is possible that you can get a FP+ for F! as you are walking to the theater.
As to when to arrive at the theater, I'd get to there 45-60 minutes before the show-time.
Even WITH having a FP or Dining Pkg. reservation, don't wait too late.
On busy nights, the CMs can stop holding the reserved sections within 20-30 minutes before show-time, and turn over any available seats to waiting walk-in guests.
Guests who learn how to take advantage of the various available "tools" and timing strategies will be able to take more control over their WDW experiences.
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Map Below-
Arrows indicate the center of the seating.
Shaded areas:
(First or Only F! performance of the evening)
Cyan= Standby (walk-in) seating
Red= Dining Package Reserved
Blue= FP+ Reserved
Purple= Can be either FP+ or Dining Plan Reserved, depending on needs.
(Second or Third F! performance of the evening)
Cyan= Standby (walk-in) seating
Red, Purple, Blue= FP+ Reserved
(Although much of the outer Blue will likely be used for Standby.)
actually other than H&V these seem to be big jumps.
