The teaser site does feature a countdown, however. There is a bug where it is based on your local time and time zone- however, source code digging has shown that the site is expected to unlock at 3:00pm Japan time. This is 6:00am GMT, and 1:00am Eastern.
This also lines up nicely with the shareholder meeting happening tomorrow, as well- within an hour and a half of the meeting starting, in fact. With this teaser site, it’s pretty clear that Falcom intends to reveal information on Sen no Kiseki IV at the meeting.
Until then, all we can do is study the image and watch the countdown eagerly.