The advance ticket page for the TOHO Cinemas Kinshicho theater in Tokyo lists the first Fate/stay night: Heaven's Feel film with an opening date of September 30. As of Sunday, the other theaters in the TOHO Cinemas chain only list the film's opening within "2017."
The staff of the Fate/stay night franchise announced last March that the film project will be split into three separate films, with the first premiering sometime in 2017. The project was initially announced in 2014 as a single film.
Tomonori Sudou (Fate/stay night: Unlimited Blade Works, Fate/Zero animation director) is directing the films, and ufotable is animating the work. Yuki Kajiura (Fate/Zero, Kara no Kyoukai) is composing the music. The initial announcement revealed that Takahiro Miura was providing the storyboards.
To sum things up, if you're not already familiar, the original Fate VN is 'three routes' - Saber, Rin and Sakura - as love interests and the stories are vastly different based on the choices you make early on in the story. Like, extremely different.
The original 2006 half-assed TV anime is sort of a low budget adaptation of the 'first' route but they threw in some weird anime original stuff near the end.
Fate/Zero is a prequel.
Fate/stay night Unlimited Blade Works (the TV series) is a faithful adaptation of the 'second' route, Rin's. The movie version was a compressed mess by a different studio.
This upcoming movie series, Heaven's Feel, is an adaptation of the 'third' route. Also, there's a very good reason why I bet this part of the VN was adapted into movies instead of for broadcast television. This 'final route' also explains a hell of a lot of what's going on in the background of the other two routes - if you were curious about what happened to certain characters or what was the reason for X, a lot gets explained with this one.