I was quite surprised to see that after writing the script they had stand-in actors do the entire script, which they then did animatics (storyboards times to the recorded audio) to, after which they edited the story. Only then did final actors record. Then redo animatics and editing before doing final animation.
Imagine my surprise watching the documentary on Hayao Miyazaki, where he has a 100 animators working on final animation, while he is still storyboarding, undecided on the ending of the movie and hasn’t even casted the voice actors!