I do not recommend using the website right away, though. In my experience, the website doesn't always work the way it is supposed to work (when an option first becomes available).
From the date you mention, I assume you are going to purchase MNSSHP tickets. They won't sell out until it gets closer to the dates, so there's no need to hurry. I'm going to wait awhile before I call to purchase mine.
No matter when you purchase the DVC or AP discounted tickets, you'll have to get them at will call so that they can verify you qualify for the discount.