If you have just the Primus package, the earliest time you can pick up your items will be on Thursday night. You'll get an e-mail soon with an assigned time to when to get in line.
Unless you have signed up for a tour or the custom class, there isn't really anything "official" to do before the lineups for package pickups begin. There may be some parts/room parties open during the day where you can buy all sorts of stuff at. There should be a bulletin board up somewhere near the dealer or panel rooms that people will post their room numbers for room sales. After you pick up your package (and tradition holds) you can line up for the club store for the as-of-yet un-revealed at show souvenirs. They will have other stuff like shirts, hats and Hasbro merch for sale as well.
