U.S. citizens may petition with U.S. Citizenship and Immigration Services for a fiancé(e) K-1 non-immigrant visa for his/her foreign-citizen fiancé(e). Additional information about the fiancé(e) visa is also available at the Department of State’s website.
An approved I-129F petition remains valid for four months from the date of USCIS’s approval. Consular officers can extend the validity of the petition (revalidate the petition), and in practice does so while the application is being processed.