We have allways gotten luggage tags from Celebrity as well as Royal.
But if you don't it's no big deal the porters will take of it. Just make sure that you know your cabin number.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
Independence of the Seas 12/29/2013 Booked!