As with many Marvel Studios movies, Avengers: Infinity War was scheduled to be released in the UK and a number of other international territories two weeks or so before it debuted in North America. Surprisingly, Disney (presumably in a bid to avoid spoilers leaking online) decided to surprise fans by having it arrive everywhere in April.
Will the same thing happen with Avengers 4, though? As of right now, it seems as if the sequel is still scheduled to hit international territories in April and North America in May. This was noted by Trailer Track Editor in Chief Anton Volkov who found an SEC filing confirming current release date plans. There's nothing to say this couldn't change, of course, and IMAX might not be clued in yet.
Considering the fact that Avengers 4 is going to be every bit as huge as its predecessor, surely Marvel Studios will look to avoid international fans spoiling it for their American cousins?
We'll have to wait and see but it could be a while until we know for sure what's happening...