After you submit these forms, you may receive a Request for Evidence (RFE) several weeks later requiring additional information or documentation. These is nothing at all unusual about receiving a single RFE, although it will delay final adjudication of your application. The more thoroughly you document your application in the first place, the less likely it is that you will receive an RFE.
You must respond promptly and thoroughly to an RFE with a full understanding of exactly what the USCIS is asking for. Consult with an experienced immigration lawyer to help you with your application.