Only a dozen theaters across the US, and one in Canada, will have the 70mm IMAX print of Rogue One.
While Rogue One: A Star Wars Story wasn’t shot in 70mm IMAX, it has been converted into that format, though not many IMAX theaters will be showing it in that way.
It’s possible that the Dunkirk preview will be in front of all IMAX showings, but that’s not confirmed.
However, if you’re lucky enough to have bought your tickets to see Rogue One in that location, Slashfilm is reporting that you’re screening will be starting about seven minutes later than the rest, as you’ll see seven minutes of Dunkirk.