I know, you're sitting there saying, "But I have plenty of time." Yes and No. According to Edvisors.com study, students who file the FAFSA in the first three months receive more than double the grant money. Keep in mind that federal aid is not distributed on a first come first served basis however, some state aid is based on first come first serve.
Remember even if you file early you can always update your form or appeal it. Federal Student Aid has as an entire section just for updates.