How far in advance do they announce promos?

[94bruin]

We're planning a May trip. I realize that they may not a run a promo for that time, but if they do, when would they announce it? I'm trying to figure out when to look at prices and start booking for the trip.

Also, if there isn't a promo, what's the best way to book to get cheapest prices. We'll be staying onsite and will need park hoppers. Last September, we did the 5 for 3 promo through Costco.