The coupon people told me it would take 3-4 weeks but I got it the following week, and you just have to mail the coupon in to RCCL- no hassle. You can apply it to the balance you owe on your cruise or use it as OBC.
Just last fall we redeemed our RCI Visa points for OBC on our Europe cruise. We got our certificate in a week and sent it in to RCI and the OBC was credited within another week. No hassel or problems at all. Went very smooth.
Majesty of the Seas - 10/03 & 02/07 & 11/08
Enchantment of the Seas - 10/04 & 10/11
Mariner of the Seas - 10/05
Vision of the Seas - 10/06 & 09/07
Carnival Liberty - 10/07
Adventure of the Seas - 9/08
Ruby Princess - 12/09
Voyager of the Seas - 9/10
Carnival Spirit - 11/10
Oasis of the Seas - 9/13