Will book quite far in advance if there are people planning a special cruise or a Cruisemates cruise, but......
If there is a really good deal, I'll book last minute. Actually I have to get a really good deal on airfare first and then will look for a deal on a cruise. The good deals on last minute cruises seem to always be available but having to pay premium rates for airfare negates the cruise prices. So if the airline has a promotional sale on flights to Ft Lauderdale or Miami, I'll look for a cruise.
We like to plan about a year out. With my husband's job, it helps to have a lot of time to plan for him to take the days off. Once he retires, I think doing spontaneous cruises when the price is right would be lots of fun.
We generally book in advance, at least 6 months. DH's job needs as much notice as possible to get a replacement for the week. Our upcoming cruise has been booked for almost a year but we were using free "bump" airline tickets and had to book the flight that far out to get it so we booked the cruise at the same time. Actually the price has steadly been going up on our cruise (now about a week and a half away and still hasn't dropped in price) so we got a much better deal booking way out then waiting until the last minute.
We have done the gammit. Price tends to dictate when we book. When the price seems rediculously low, we book it even if it may not be our first choice for ship or itinerary. Dates are important because of my profession which has very inflexible vacation schedules.
Yesterday while I was at the travel agency I couldn´t believe I was sitting there talking about cruises that were one year away. All I could think to myself was "is this normal?" and from your replies, I guess it is. The travel agent said "the more important ship, destination and cabin is, the earlier you should book." I guess she is right.
Tweety´s comment about airfare hit home here. There some wonderful cruises available last minute but the airfare was a disaster for both US based cruises and European. I forgot to ask about package last minute deals...will have to do that next time.