Hi petros, hope you're doing well. 🙂
NYU is rolling admissions, so the letters should be sent out as they make their decisions. I interviewed on November 3rd, and I received notification of my acceptance on November 29th. They actually sent me an e-mail, basically stating, "Congratulations! You've been accepted, and we've just put a letter in the mail for you. If you do not receive it within five days, please contact our office," etc.
That's interesting, their remark about no acceptances until ~ New Years! When I interviewed there, I asked some of the students when I should expect to hear the final decision, and they all told me two to four weeks.
I also believe that one other person on this board received a decision letter, before mine, actually. If you check the thread listing all three outcomes (acceptances, waitlists, & rejections), you might be able to identify the poster about whom I'm thinking.
I hope that this helps petros. Please, let me know if I can do anything further!