They usually have the contest up in place days or weeks in advance of the contest, allowing you to sign up, and then only filling in your predictions once the field is official. Note the World Cup Bracket Predictor is already up. Several times in the past, I have created leagues in advance of the tournament bracket/bowl games were announced, and just making the BG post when picks are able to be made.
If it does happen this year, it's going to be differently than anything else I've seen them do, which makes me think it's not going to happen at all.
