The visa application can be done online and you will collect specific documents that will be needed at your interview. Interviews are required for applicants between the ages of 17 and 79. You can schedule an interview with the U.S. Embassy or Consulate. Visa processing times may vary, but as soon as you receive it, you will be granted permission to enter the United States. You can extend your stay when you work in compliance with U.S. Citizenship and Immigration Services (USCIS).