App was filed 3 weeks ago by citizen petitioner. What is expected from hereon?

Could you please explain more? What country we are talking about here? What type of visa?

Sponsor for undocumented wife. Both in USA

Does the term "undocumented" here mean overstayed the visa or illegally enter US without inspection?

If this is the overstay case, then immigration attorney can take care of the matter without beneficiary leaving the country. If this is the case of entering US without inspection, then you will receive notice of denial and deportation warrant unless you have immigration attorney file a waiver on your behalf.

Please consult immigration attorney, don't try to proceed by yourself. You may make it more complicated.