Unless they ask, (and you tell them, whether via interview question or secondary app) they do not have access to where you've applied or been accepted until May 1st. After May 1st, they are granted access to that information from AADSAS in order to see if anyone that they have accepted has multiple deposits placed. This allows them to force people to make their decision or they'll just repeal their acceptance so they don't hold up spots for other people.
This info is via the admissions person from USC who told us this information at the interview....