I went last year over Easter and the only discount that came out was for AP holders. I ended up renting points at BWI, which came to $160 a nite. We also stayed at POR for $200 a nite. I can't believe I paid that much for POR, but it is peak season. The week before and after Easter will not get discounted.
I would book now. It will be crowded and you don't want to miss out on the room altogether. If a code does come out you can always try to have the reservation changed. If you are a AAA member you can check to see if there are any rooms available with a AAA discount. May only be a 10 percent discount, but better than nothing.
If you plan to stay at Poly even without a discount, I would book now. Discounts during Easter are rare, so I would not take a chance of not getting a room. Normally I would say wait, but not during a busy time like that.