It will be set in year 11 of Panem, or 64 years before Katniss and Peeta compete and live to tell about it. The book is scheduled to be released in the summer of 2020.
I had forgotten about this until I saw that Veronica Roth thread. FTR, I started reading “Divergent” but lost interest about 2/3 of the way through the first book but finished it anyway.