For us, we booked our cruise in May 2018 sailing this month, November 2018. The reason we purchased the pre-paid beverage cards is because it was easier for budgeting. Instead of us owing money at the end of cruise we just added money every month (May to November) to either on-board credit, a beverage card, etc. This is just our preference as it didn't seem like a big deal to just spend $50-$100 a month (May to November) and waiting for us when we board on our account or on cards to use onboard. Everyone is different but the biggest advantage is that you can purchase a $50 value soda card for $25 dollars before you sail.