回複：留學生入關後必須10天之內到學校報到嗎？

什麽時候報到，取決於學校要求（when F1 starts）。

但你侄女可以在F1 開始前30天內入境。

http://travel.state.gov/visa/temp/types/types_1268.html

Students are advised of the Department of Homeland Security regulation which requires that all initial or beginning students enter the U.S. 30 days or less in advance of the course of study start/report date as shown on the Form I-20. Please consider this date carefully when making travel plans to the U.S.