The official Twitter page for Sword Art Online announced that US nationwide theater tickets for Sword Art Online The Movie: Ordinal Scale will go on sale starting January 6, 2017 at 12 pm (PST) or 3 pm (EST). You can check out their Twitter post announcing the sell date below.

??U.S. nationwide theater tickets go on sale TOMORROW (1/6/17) at 12 p.m. (PST)!!
Get them at: https://t.co/G6OBuITw90#saomovieus ?? pic.twitter.com/VKgbKBNHcI

— Sword Art Online (@SwordArtUSA) January 5, 2017

Details including which theaters will be available on our official homepage (https://t.co/vox2p1Qsp9) TOMORROW (1/6/17). #saomovieus

— Sword Art Online (@SwordArtUSA) January 5, 2017

You can purchase tickets for the movie on the film’s official website HERE. A list of theaters will also be made available on January 6.

A prologue of the film is provided by Aniplex USA:

In 2022, the world of virtual reality was upended by the arrival of a new invention from a genius programmer, Akihiko Kayaba. Called NerveGear, it was the first full-dive system and with it, came endless possibilities to VRMMORPGs.
In 2026, a new machine called the Augma is developed to compete against the NerveGear and its successor, the Amusphere. A next-gen wearable device, the Augma doesn’t have a full-dive function like its predecessors. Instead, it uses Augmented Reality (AR) to get players into the game. It is safe, user-friendly and lets users play while they are conscious, making it an instant hit on the market. The most popular game on the system is “Ordinal Scale” (aka: OS), an ARMMORPG developed exclusively for the Augma.
Asuna and the gang have already been playing OS for a while, by the time Kirito decides to join them. They’re about to find out that Ordinal Scale isn’t all fun and games…