Congrats on the upcoming wedding. You will need to check the Early bird rules, I am pretty sure that it is "refundable" credit where you get unused OBC at the end of the cruise.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014