The parent income has the biggest impact and parent assets over the parent asset protection allowance.
For 2016-17 FAFSA student income has an income protection allowance of $6,400 and also an allowance for federal, state, social security taxes.
The student doesn’t have asset protection allowance so putting his earnings in the 529 is a good idea since it counts as parent asset.
2015 income will be used for 2016-17 and 2017-18 FAFSA.
But some LACs might also use the CSS profile. The aid calculation will be different.
Have you tried running the net price calculators with different student incomes and assets to see the changes?