According to dining packages available for the show on DisneyWorld.com, Rivers of Light will officially debut on or around May 1st, 2017. The dining packages offering reserved viewing space for the show will begin to be offered on May 1st, so the show would have to debut by then. Dining packages will be available for booking 180 days in advance should all go according to plan this time.
For some reason, the Tiffins package is not actually listed along with Flame Tree Barbecue and Tusker House, but the official information confirms that 3 restaurants will be a part of the dining package.
UPDATE: The page has since been removed from DisneyWorld.com, so we will have to wait and see if this was an error on Disney’s part or if we are really going to have to wait until May for Rivers of Light to debut.