After USCIS approves your petition, they will transfer your case to the Department of State's National Visa Center (NVC) for pre-processing. The first step in this processing is the creation of your case in the system. Once this is complete, you will receive a Welcome Letter by e-mail or physical mail.  

Once you submit your fees, forms, and supporting documents to NVC, they will review your case to ensure you provided all the documentation required to schedule the immigrant visa interview. Interviews are based on the availability of appointments offered at the Embassy/Consulate.