From 3 Steps to More College Financial Aid From FAFSA:
“Because some aid is awarded on a first-come, first-served basis, the sooner you file your FAFSA, the better. [Financial aid expert, Mark] Kantrowitz says his research indicates that families who file before March 30 typically get more than twice as much aid as those who do it later. If you haven’t filed your taxes for 2015 yet, you can fill out the FAFSA with estimates based on your 2014 tax forms and update your FAFSA once you’ve finished your 2015 return.”