Affidavite of support

When does it is required to submit Affidavite of support?At the time of filing I-30(Immediate relative living outside of US) or at the time of interview?Please help.

When does it is required to submit Affidavite of support?At the time of filing I-30(Immediate relative living outside of US) or at the time of interview?Please help.

For persons who are living outside the United States for them Affidavit of Support is filed when the person's interview is nearing.
Good luck.