Once you are granted a U.S. entrance visa, notify the school of your expected arrival date, and obtain a new I-20 if the dates have been deferred. Also, be sure to confirm your housing and transportation arrangements in advance of your departure from your home country. Keep in mind that you can enter the U.S. no more than 30 days before your program start date.
The Customs and Border Protection inspector will stamp your Form I-20 and Form I-94 (Arrival-Departure Record Form) after determining that you are eligible for entry. This document is proof that you entered the U.S. legally. You should keep the Form I-94 safe throughout your stay in the U.S.