I have gathered data from a few different sources on holiday tipping from 2013 as the 2014 information has not been published yet. Links are enclosed below, but the general consensus is that cash is king and early disbursement of tips is very much appreciated – as early as right before Thanksgiving. The staff need resources and time to shop for their own holiday gifts! Other factors that come into play are building size, family size and length of residency in the building.

http://ny.curbed.com/archives/2013/12/09/how_much_to_give_your_building_staff_the_annual_guide.php

http://www.brickunderground.com/blog/2013/11/doormen_speak_whats_a_fair_tip_how_the_tipping_system_should_change_who_gets_the_best

http://www.brickunderground.com/blog/2013/11/brickundergrounds_2013_holiday_tipping_guide