Remember, discount codes are a WDW incentive to guests to fill empty rooms. If they are substantially booked, discount codes probably will be limited, if released at all. And this year, WDW seems to be filling rooms quite well!
If room price is an issue, you might want to book back-up accommodations at rack rate at a less expensive resort, just in case the discount codes don't materialize. Then you can apply the discount if it becomes available for your preferred resort and cancel the other one.