An update from scified member:
UPDATE: Forum member Leto suggests that the numeric code counts to December 22nd, 12:05, 2104. The year 2104 is when Alien: Covenant takes place (10 years after Prometheus). It seems Fox will release either a teaser for the trailer, or the trailer in full on December 22nd at 12:05! Whether that be AM or PM we're unsure, as well as what time zone used. As we learn more we will keep you updated!