hey dude, as far as i know, you have to first get engaged then only file for the K1 visa for your fiance'. you will need to provide concrete proofs while filing for the K-1 visa that you and the person you are sponsoring K-1 visa (i.e. your fiance') have indeed been engaged. for more information on this, you can check K-1 visa requirements and procedures on google. hope this helps. Good Luck!