Servers will come offline at 8am PDT.
UPDATE: The downtime will occur on Friday, June 15 at 8am PDT. Servers are expected to be offline for at least 1 hour.
According to today's SOE Community Webcast, the Shrouded Glade Under Attack event is scheduled to start tonight! No time was given but we're guessing that 9pm Pacific, when a lot of updates occur, is likely. Watch for announcements in-game, on Facebook, or on the Official Forums!
You can watch a video of the webcast on SOE's Twitch TV page.