My comments are only based on my experience so you can take that with a grain of salt. Last Oct Princess announced a new pricing policy which was going to reward people who booked early with the lowest prices and not have as many price reductions as the the sailing date got nearer. We booked a mini suite when a particular cruise on the Sum Princess was offered and saw the price go up over 50% in the last 7 months. Then they introduced the Sanctuary staterooms for some balcony, mini suite and all suite guests and grandfathered in all those who were already booked in stateroom in those areas that qualified. The end result is that the cabin next to ours now goes for twice what we booked it for.
As far as booking at the last moment, think that after the 90 day period where people can opt out and get a full refund is the best time to look for deals. In looking for cruises after my busy season came across 1 penthouse suite left approx 2 months before the cruise which I am sure someone recently opted out of. Got a reasonable discount off list (not nearly as much as my aforementioned counter offer for the same type of stateroom) but enough to make me book it on the spot. Less than a week later the cruise was listed as sold out.