Currently, the first part of the two-part film is scheduled for release on May 4, 2018 – there’s plenty of time to go until then and we’re likely going to find out more about the film in the coming months as it’s too early to talk about it in detail right now.
The second part is going to come out one year after that, so both films are apparently being produced simultaneously or at least with some overlap in the work between them.
Which would certainly make sense, considering that they share so much of their cast and premise. We can easily see the producers doing something like taking care of all the shooting first, and then working on post-production side by side for both films.
That could also open up the doors to some interesting additions to the films, such as hidden easter eggs scattered throughout both parts. That definitely wouldn’t be out of the question for what we’ve seen from the Marvel cinematic universe so far, as the producers involved in these projects definitely seem to have a knack for giving their fans some hidden details to hunt after. And on the other hand, fans obviously love that too, so it’s a win for everyone involved.