<p>Understand that as an international whether you can get need-based financial aid at all depends on college since public universities and many privates do not provide need-based financial aid to internationals. </p>
<p>As to whether you can apply later assuming college offers any aid to internationals, it is usually an annual event. Those who apply in spring will get need based aid for first year and they will need to to update financial info for second year and those who did not apply for first year can do so for second year or third or fourth.</p>
<p>My best guess is it would be rare for colleges to give an intnl aid later if they did not grant them aid as a freshmen. The possible exceptions would be the handful of schools that are need blind and meet need for intnls like HYPDA. I would call your schools and ask.</p>