Nopers, They don't want to give much after you get out of Cancellation Period. Which is the day Final Payment is due. They don't like to change booking codes after then, but if your code goes down they will sometimes give the OBC.
See, sometimes your original code has an "Upgrade" such as buy 6A get 6D, then when you call later about it going down that offer may not be available. The price for 6A may have went down, but you won't be getting 6D Empress Deck.
Sorry to be technical, but went through it myself as a CCL Agent. Example, my Resident rate went lower for 6A than my Past Guest rate, but it did not include 6A to 6D Upgrade.
I think one should start figuring out where they want to go about 8 months out, and start serious shopping about 6 months out. Pick your cabin if doing assigned, and if it goes down, ride it down untill final payment. Then still be persistent if you booked a guarantee and don't care about a higher deck.
Prices do go higher on specialty cruises, when school is out cruises, and Holiday cruises, and New Ships.