The current offer ends 8/15. Typically the room discount bounce back offer for the upcoming year (2018) will start in November/December, so you may have to wait until you check in. With Disney's recent cutback on discounts, it is anyone's guess as to what the offer (if any) will be.
This year was 20% off select value, 25% off select moderate and 30% off select deluxe during certain timeframes (most holiday periods excluded). Often the discount only applied to the more expensive room category.