I second a+j's answer. From my personal experience with the Naples consulate, don't even start the K1 visa process if you already know that the sponsor won't be working by the time of your interview. My fiance was looking for jobs when I had my interview in December. We are a young couple and we both have recently graduated just a few months ago, but the consul didn't seem to consider this as a justification. Even though we had his mom as a joint-sponsor we got a flat denial. What the consul told me during the interview is that they do accept joint-sponsors for K1 visas but only if the primary sponsor has a current income and makes at least 100% of the poverty line. If you think your sponsor won't be working for awhile just get married and apply for the CR1.
Our story has a happy ending, but I know what it means facing the shock of a denial after having spent so much money and time apart. That's why I hope that sharing my experience will prevent other couples from making the same mistake. Good luck!
Eli&Dan got a reaction from J & L in K1 Visa application using a co-sponsor