The meet and greet was originally supposed to go through January 4th, but has now been extended to last until January 31st[^f1203].
For anyone who wants to meet Anna and Elsa, I highly recommend being in line at 10:30am (for the 11:00am meeting session.) The amount of people that can be admitted for a given session is very short, so if you miss this first session, it could be a very, very long wait.
[^f1203]: I would not be surprised if it was extended again, too.