关于DS2019入境时间的规定

1. 美国国务院规定：
http://chinese.usembassy-china.org.cn/niv_exchange.html
“交流访问学者签证的持有者只能比项目初始日期提前30天或更少天数入境美国。返美继续同一交流项目的申请人不受此限制。”
因此，只能在DS2019开始时间30天内入境，否则，会被拒绝入境。

2. 美国移民局规定：ttp://www.ice.gov/sevis/factsheet/100104ent_exchng_fs.htm
“Folling Admission Into the United States
Exchange Visitors must report to their Exchange Visitor Program sponsor within 30 days of the program begin date identified in line 3 of the DS 2019 to have their participation in the program activity validated. Exchange Visitors in programs beginning with “G” listed in item 2 of the DS 2019, and who are being sponsored for less than 30 days, must have their sponsor validate their participation prior to the end date listed in Item 3 of the DS 2019. Failure to have participation validated will result in an automatic invalidated SEVIS record."
美国移民局要求：J1交流学者及其雇主必须在DS2019开始时间的30天内，报告他们是否参加该交流项目项目。因此一般学校都会要求你在项目开始的30天内入境。
因此，各校ISSS小米会告诉你，入境时间比DS2019开始时间退后超过30天，换表或更改sevis信息。
比如UCSC规定：ttp://oie.ucsc.edu/is3/scholar/j1/prearrival.html
"If your entry to the U.S. will be delayed beyond your projected start date in Box 3 of the DS-2019 contact ISSS at jvisa@ucsc.edu (put J-1 Scholar in the subject line) and your department for instructions. "

综上所述，拿到DS2019表后，请在开始时间的前后30天内入境。如果推延，与学校ISSS联系，换表或更改sevis信息。