I am a research analyst at Vanderbilt (also applied there), and I was told by the director (Jo-Anne Bachorowski) that interview invitations for the PhD usually go out by the end of the second week in January. I know they haven't gone out yet.
I know for Duke invitations go out "mid-January".
Hope that helps!
I applied to:
Duke
UNC Chapel Hill
Vanderbilt
University of Kentucky
Georgia State
Emory
University of Florida
University of South Florida
University of Miami
University of California San Diego/San Diego State Joint Program
Now let's all do some yoga.