I think you have enough information about the how book for VFS Chennai Appointment. I want to tell you about the visa processing time.
Processing time of Visa is usually 2 business days; the processing time of might differ on individual conditions and other individual requirements. In some other cases administrative processing may need. In these cases American embassy or consulate works carefully to reduce any impact on your travel.
The following is the procedure to make an appointment to apply for VFS in Chennai:
You have to send mail to VFS to this E-mail i.d - email@example.com
You should include your name and surname, visa category, passport number, your residence address, preferred date and time to reach the Visa application centre.
VFS will send revert to your mail by the end of the day including the confirmation of the appointment.
You can save your time by making a prior appointment before visiting the visa application centre. You can book an appointment by visiting the VFS online appointment system. In order to get your visa on time it is very necessary to fix the appointment with U.S. Embassy / Consulate on time. Sometimes the waiting time is more so, the best thing to do would be to apply at an earlier time.