No interview will be scheduled until after NVC has an approvable affidavit of support. If your husband is an employee, and his employer will transfer him to work in the USA, then a letter offering that job with the same company in the USA, will suffice. If he is self employed, and the income will continue from the same source, that's fine too. If neither, then the best solution without a joint sponsor, is for him to find a job in the USA as soon as possible, and go back to work there.
Separation is far more common in this process, than not.