I don't think they will do that. I think they will send them right when you order them.
If you want to spend a designated amount of money each month. You can put money in a jar each month and then a month before the cruise buy your drink coupons. That way they will all come at the same time and you don't have to use all the money from one month.
Carnival Dream for Thanksgiving
Eastern Caribbean- 11/20/2010
Carnival Ecstasy (4 Day Baja Mexico) 2003
Carnival Pride (7 Day Mexican Riviera) 2007
Carnival Spirit (8 Day Exotic Mexican Riviera) 2007
Carnival Freedom (7 Day Western Caribbean) 2008
Carnival Elation (4 Day Baja Mexico) 2009
Carnival Spirit (7 Day Southbound Alaska) 2009