This is a good topic as it may change your departure plans. I just finished the interview process for the K1 visa with my my fiance here in Ciudad Juarez. The original letter we received for the immigration interview, was actually an appointment to drop of several documents ( fiance passport, birth certificate, background check, DS-160, and appointment letter). After providing the documents, she was given an appointment for the following morning for the interview and provide the remaining paperwork (sponsor birth certificate and proof of prior divorce). They did not collect our I-134 financial documents. She was informed of approval at the end of the interview and they estimated a week to receive her passport and visa back via DHL. Best of luck everyone!