Acquiring a Visa Stamp
It is strongly recommended that you allow ample time to obtain the appropriate visa stamp from a U.S. Embassy or Consulate abroad. Per the U.S. Department of State: U.S. Embassies strongly encourage intending travelers to apply for visa stamps well in advance of their proposed journey, and to always refrain from making irrevocable travel plans until the visa stamp has been issued and they are in receipt of their passport and visa stamp. Visa stamp issuance to certain individuals may be very slow due to security clearances. Plan your travel carefully and consult the visa wait times posted on the U.S Department of State website.
All international scholars and students planning to apply for a visa stamp should first thoroughly read the U.S. Consulate’s website to know that consulate’s specific visa stamp application requirements. Be prepared for a brief interview with the consular officer.
The visa stamp, once issued, includes an adhesive stamp on a page in the passport. This stamp is your "door key" to enter the U.S. The visa stamp has an expiration date signifying only the amount of time during which one can enter the U.S. and does not affect how long one can stay in the U.S.
The length of stay is determined by date on the I-94 Admission Record. The I-94 Admission Record for most F-1 students and J-1 exchange visitors is marked "D/S," meaning, duration of status. Duration of status means that the person is permitted to remain in the U.S. until the program end date displayed in the Program of Study on the I-20 or area #3 on the DS-2019.