Last year I called the first week in July for the HRH during Easter 2001, and found out about the Ent. rate on this forum, so switched to that a few weeks later. When I called back in the fall to add a date the Ent. rate was already sold out.
I'm booked for next Easter, but I agree the best thing to do is keep checking, and whenever anyone hits the discount, spread the news here. They also told me to call back in late fall for the discount, but I find it hard to believe it'll take that long.