I feel like December would be a much better time than May, though. Transformers (a spinoff of a dying series), Aquaman (another DCEU film not destined for much), and Spider-Verse (a lower key family film) are much smaller targets to go up against in comparison to Infinity War (basically the guaranteed biggest blockbuster of the year), Deadpool (one of the biggest new superheroes in recent years), and Incredibles (a sequel with 14 years worth of pent up demand).
Although really, I'd move the film to late August above all else. Literally the only competition it'll have at that time is Christopher Robin.