A filming start next April, with a debut in May 2019, would give Star Wars: Episode IX a sizeable 25 month window.
Either way, it opens a can of worms – one that fans of Star Wars should enjoy following and obsessing about over the course of the next few years.
If we bump the film back to December of that year, then the production cycle grows to 32 months.
This means that either (a) the information is incorrect or that (b) Disney executives, Lucasfilm President Kathleen Kennedy, and co-writer/director Colin Trevorrow are all so concerned about sticking the landing perfectly right – since this may very well be the swan song to the entire Skywalker family story and all – that they’ve built themselves a filmmaking lifecycle that more closely mirrors what George Lucas did with all six of his installments; giving himself plenty of time and room for reshoots or writing entirely new material, based on how the movie evolves in the editing room.