The Game of Thrones prequel series, widely being referred to as The Long Night, has gotten an official production start window.

Reported by EW, HBO programming president Casey Bloys says the series will begin production sometime in early summer. While a specific starting date on production has not yet been announced, Bloys has previously claimed it won’t air until at least a year after Game of Thrones has finished. As its final episode is set to air on May 19, 2019, it appears the prequel series won’t air until summer 2020 at the earliest.

EW also reports that a writers room is allegedly already in operation for this prequel series, and it’s working on additional scripts if HBO green-lights more episodes.

In May 2017, HBO closed deals for writers to begin work on four potential Game of Thrones prequel series – a fifth script was also reportedly in the works. We later found out that The Long Night project will likely be set 5,000 years before the events of Game of Thrones, and will be based on a concept that X-Men: First Class’ Jane Goldman developed with George R.R. Martin.

In October 2018, HBO announced that Naomi Watts had been cast in a lead role in the project, and later revealed eight more cast members.

Colin Stevens is a news writer for IGN. Follow him on Twitter.