Jake

What if I lost my job(company goes under)after I have sent in the
papers and before we got the interview? I have a joint sponsor just in
case, and he is my potential new boss. But if I lost my job there
would be a month or month and a half window of unemployment. Am I
okay, because of the joint sponsor of am I screwed?

Just Jenney

If your employment/income situation has changed, you need to complete a new I-864 to bring with you to your AOS interview. Depending on the circumstances, it will either reflect that you are unemployed at the time of the interview, or will reflect and document your new job and income (letter of employment from your new employer, etc.)

~ Jenney

ian-mstm

I'm not sure English is your first language, but it sounds as though you're asking whether or not a period of unemployment will affect you at the interview. The answer, of course, is no... but it has nothing to do with your having a joint sponsor. As Jenney correctly indicates, if your financial situation changes, that will need to be reflected in a new I-864.

Ian