Even if you don't have your field kit yet, you can still take a look at the model pictures and guess what your robot's tasks might be. We won't know for sure until August 26th, so let your team's imagination really run free.
Lots of teams like to get together during August or after they form in September to have a "build party". Team members can get familiar with uses for different types of LEGO pieces and have the mission models ready to go.
For rookie coaches, and others who'd like to get more comfortable with FLL, keep an eye on the FLL Coach Calls that will be listed at
http://www.firstlegoleague.org/challenge/teamresources (plus, you can start by listening to some of the recordings from last year--the basics of mentoring a team apply every year--only the specifics of the robot game and the project challenge should change.) There is a lot of good material linked from the Coach/Team Resources page, so try to check there multiple times during the season for help.
From the FLL Challenge website, you'll be able to link to FAQs about this year's project: