June 2022
Should be when the final chapter of Act 2 Book 1 based on what i read so goes as follow and feel free to correct me.
Dec 2020 if all goes well chapter 1 is released...June 2021 chapter 2 with chapter 3 in December 2021 and finally June 2022 final chapter.
This is the longest i seen for a Story Quest and really appreciate the long breaks in between not only it will allow them to craft a perfect story but also allow summoners like me get a chance to not fall behind like we are with Act 6 which is fully out lol