<p>Eric, the Part 1 is really for USC to open a file. It is not part of the materials that admission committees will base their decisions on. Your later SAT scores can be updated on Part 2. My D also had an improved SAT score in October after submission of Part 1.
There is no EA at USC, …however be aware that if you’d like to be considered for a merit scholarship, you must submit your Part 2 by an earlier date as indicated on the website. (Last year I believe it was Dec 10). As mdcissp mentions above, all decisions are made from late January through April.</p>