The best way to make sure you get the best deal is to go ahead and book on opening day. Then, when you are onboard your next cruise, go to the future cruise desk and ask them to re-shop the cruise. They can figure out if it is a better deal to keep the cabin you have booked at opening day prices, or to cancel that booking and book a new one with the current prices but the benefits of the OBB credit and the 10% off. Which one works out best depends on a lot of factors - sometimes the cruise prices climb quickly, which can negate the discount and OBB credit, but other times the prices rise more slowly - but you don't know what will happen in advance - better to be prepared!
Aby