You can add it later, but I think there's a 60 day prior time frame. I just added it last week for our May cruise from CSA travel, which seems to come highly recommended from these boards. It was only $85 for my family of 4 for 4 nights, cruise only. I just felt I'd rather be safe than sorry, never knowing when a family member could become ill or you'd get called back for a funeral, etc...