Set expectations
Refer to the first page of the Setting Overview. Ask everyone if they're comfortable with the players' agenda and principles. Clarify and answer questions. Emphasize the importance of collaboration.
Explain that you have an agenda and principles, too. Specifically, your agenda is to:
- Portray a rich and mysterious world
- Punctuate their lives with adventure
- Play to find out what happens
Make it clear that you'll be fleshing out the world together. There are no "official" answers to many of the questions raised by the Setting Overview. There are many blanks to fill in. You (the GM) have a setting guide, but it's mostly filled with ideas rather than truths.