In case of a delay and you are unable to enter the U.S. within 30 days of the initial start date of your program, as indicated on the DS-2019, you MUST notify us immediately so that we can update your DS-2019 for a later entry date. Failure to do so may cause your status to become INVALID and you may not be allowed to enter the country.
这说的很清楚，就是再晚不能超过1个月。
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