Can anyone please inform me?

I am going to be interviewed by immigration soon but I am not sure how long will it take for them to call me up? If anyone know please inform me. My situation is this: I am a U.S. citizen, I got married in October of last year, my husband is right now in el salvador and is waiting for immigration to accept his presence back in the U.S. This is why I am asking, how long does it take for immigration to call for an interview?