Once your K1 Fiance Visa
application has been approved by USCIS, you will need to start working with the US Embassy location in the country where your fiancé lives. Every USCIS approval notice has an expiration date of 4 months. If you need more time to complete your work with the US Embassy, you can contact the Embassy and ask for further validation time.
Every Embassy around the world has its own procedures for processing K1 Fiance Visas. Some US Embassy locations work directly with the beneficiary and others use a processing center affiliated with the Embassy. Either way, you will be sent an notice and/or link for how to proceed. This may come from the Embassy or the NVC. You must wait for the Embassy or NVC to contact you before you can start working with the Embassy. At some point, you will be given the information that you will need or directed to a link that identifies the forms and documents that must be completed before you can schedule your interview. Your embassy instructions will also let you know how to pay the Embassy processing fee and where and when to have your medical exam. Once everything is completed, you can then schedule your interview.
From my experience, it takes about one month after being approved by USCIS to receive your Embassy notice and/or instructions and then another 2 months working with the Embassy to actually obtain your visa.