Affidavit of suppor

Hey all, I’m filing for my father, I-130 approved after about 11 months (yay! It’s been 20 years!) . He is Mexican citizen living in Mexico still. We just paid all fees after getting his NVC welcome letter in less and than 48 hours after I-130 approval. My income as a family of 4 is 3k less than the min but my sister whom we share the same mother and father is Mets the income for her family plus my father as will be able to joint sponsor it seems. Should I have us both fill and submit these at the same time since I know my income is a bit shy of the requirement of a total house hold of 5 (with my father) or is it better to wait for them to ask for a go sponsor? I understand this is not legal advice and I appreciate any times!