The first movie of the series, Digimon Adventure tri. Saikai was released on 2015-11-21, with a retail release of 2015-12-18. This movie consisted of 4 episodes, and is the first part of a 6-movie (or 24 episode) series1.
According to an Anime News Network article, the second part of the series of movies will premier on 2016-03-12 in Japanese theaters; they also list the Crunchyroll release as March 2016.
Originally, I had heard that these movies will be released once a year for 6 years. However, that would make the final chapter have a release date of 2021. Is there any information regarding the schedule of release for this series of movies?