You can contact USCIS to see if an appointment letter can be sent sooner, but it is not likely. Once you receive the letter, you could attempt to go to the location sooner than your appointment. You may be able to have your biometrics captured earlier under the circumstances. If you receive the biometrics appointment notice after it becomes difficult for you to travel, you can call the number on the bottom of the notice to reschedule the appointment.
Answered on Nov 18th, 2015 at 6:29 AM