Well, it certainly won't hurt, but gear oil lasts forever. You could go way over 24K without a problem, but I wouldn't. I would agree changing it first time around 12K with synthetic (to get the initial break-in metal out).... Environmentally, it is a waste at every oil change IMHO.
+1 on the environment.
I changed mine with my first oil change @24K+ (bike had ~24K on it when I got it). The dealer I bought it from may have changed it when they prepped the bike for resale, but all I know is that the stuff that came out when I drained it looked and smelled exactly like the replacement lube fresh out of the bottle that I put in it. I read somewhere that a few new ST owners had discovered thick black, gooey stuff in their final drives when doing the initial 600-mile service, so it would certainly be a good idea to change it then and at the next oil change after that just for insurance, but if the lube drained from the FD the 2nd time still looked good I would recommend either following Honda's recommended schedule, or 10-12K minimum intervals if that provides you greater peace of mind.
I realize that comparing SUVs to motorcycles is like apples to oranges, but I suspect the loads subjected to the final drives in a 5000+ lb SUV may be a little greater than those in our ST final drives. A case in point: I remember the one and only time I took my Expedition to a certain local business (which will remain nameless) for routine maintenance, the service manager brought the differential "drain plug" to show me the contaminates on it and "informed" me that Ford recommends the fluid gets changed every 30K. It was obvious to me he was trying to pull a fast one on an unsuspecting customer (how did he remove the drain plug without draining the diff lube? - DUH!) and I told him thanks, but no thanks. I later looked underneath and confirmed my suspicions - the Expedition's diff DOESN'T EVEN HAVE a drain plug. I then dug out the owner's manual and looked up the recommended maintenance schedule, and learned that Ford doesn't recommend changing the diff lube unless it's been under water.
If I ever discover my ST's FD under water (rain doesn't count) I'll certainly change the gear oil ASAP, but otherwise it will be at least 10-12K between changes, if not the 24K interval recommended by Honda.
That's my story and I'm stickin' to it.