The smart money is on January 3rd.

David Yepsen covered most of the bases in his column yesterday, but here are a couple more reasons:

• Florida isn't backing down.  With their jump the South Carolina Democrats will likely follow their Republican statemates and go on the 19th of January, and Michigan will feel justified in violating the DNC scheduling rules as well.
• New Hampshire SOS Bill Gardner wants to go on a Tuesday.  While the New Hampshire reworked their law so that he can put it on any day just so long as it is the first primary.  In case you're just tuning in, Gardner is the God of the Primary in New Hampshire.  Even if Michigan backs off, the latest Tuesday available is January 8th.

If New Hampshire is on the 8th, then legally we can go no earlier than the 31st of December.  Fat chance.  Since December is basically out of the picture barring further excitement, the only possible dates are the 2nd, 3rd, 4th, 5th, 6th, and 7th, and the earlier the better.  The 2nd will be ruled out as too close to New Year's Day, although really anyone who hasn't slept off their hangover from drinking 43 hours before is probably not a likely caucus attendee anyway.  The 3rd seems like the sweet spot between giving people at least a little time to think about politics again and giving the winners a measurable bump in New Hampshire.