The first scene in the movie shows the back of Grindy’s head (before he takes Graves’s form) and he attacks 5 Aurors. According to the screenplay, this scene is somewhere in Europe e.i. not New York
The interesting part that isn’t made explicit in the movie is this attack happened the night before Newt arrived in New York because
scene 2 (which is Newt arriving in New York) is set the very next morning.
Grindelwald arrived in New York around the same time Newt did. (possibly on the same boat, even…?)
So this means
Grindelwald attacked and stole Percival’s identity sometime between his attack in Europe and ‘Mr Graves’ at the obscurist disturbance the next day.
The amount of time Grindy spent with Credence is dramatically reduced, compared to some other theories I have read.
Also brings back the question as to why Grindelwald took Graves’s place and not Tina’s…
