The official blog at the EVE Online site has been updated with information about the next update scheduled to go live on January 18th. Devs will be lulling the server hamsters to sleep and probing them with alien instruments before restarting things again later in the day. With the update, the Sansha will arrive.
One important note: If, on the 18th of January, you find yourself flying around New Eden unable to see any Incursions on the starmap, there is a good reason for it. Rather than just haphazardly throwing the content onto TQ, we'll be opening it in what we hope is a spectacular-but-oh-so-carefully-staged manner, which means you won't see it right away. Don't panic - the spiky space zombies are still coming, but they'd rather jump out of a cake in lingerie, swinging assault rifles by the light of fireworks while singing whatever song space zombies sing, than simply "be there" when the server starts.
Keep your eye open for events and just generally things being a little "out of place" following the Incursion deployment.