I try to book as soon as they come out, usually JS. That way you have a wider choice of rooms to select, expecially if you like specific types like aft or hump rooms. I try to monitor the prices a couple of times a week. I've found at least for JS the prices remained relatively stable between a couple of price points depending on the "sale" taking place, but do trend higher as you get closer to the sail date. But, if you are dilgent, you can catch a deal every now and then. A couple of years ago, about on Oasis they had a GS for less than JS, so I quickly called RCI and changed rooms. I have found that in looking at interior, window and balcony, there can be more significant price fluctuations. For example, for a cruise this october, last week the guaranteed balcony was $1,276. Today it is $745. There was no change to the JS price....go figure...