If you are staying off-site, you can book 180 days in advance of when you want to dine. If you are on-site you can book 180 days + 10 before. So, if for example, your first date of stay was 1st March, you could book all your dining 180 days before 1st March but could also book for dining up to and including 11th March (I think). Hope that makes sense - it's quite hard to explain.