Is there a set date for Sword Art Online Ordinal Scale to be released on DVD?
I don't know about an international release, but the movie will be released in Japan on September 26th or 27th, 2017. CDJapan has both the Japanese DVD and Blu-ray versions available for pre-order now. The Japanese copies have been confirmed to have English subtitles.

Japanese source on AnimeAnime.jp

English site using the AnimeAnime.jp site as a source