The first stage in a National Interest Waiver (NIW) case is the filing of the Form I-140 Petition with the USCIS. The NIW application is within the EB2 preference category, and is subject to the same backlogs as other EB2 labor certification cases, even though they may enjoy the benefit of not having to get a Labor Certification or require employer sponsorship. Nationals from India and China, who are applying in the EB2 preference category, are subject to a backlog in visa number availability, 

The backlog in visa numbers for Indian nationals is measured in years. People from China are also subject to a visa backlog, but the wait time for these individuals is presently shorter. The lack of visa numbers is due to U.S. limits on the numbers of individuals who can immigrate permanently to the United States each year. This is controlled by the issuance of constrained immigrant visa numbers and compounded by per-country limits. To reach the second and final stage of the green card process, which is either an adjustment of status (Form I-485 application) or a consular processing for an immigrant visa, there must be a visa number available in the particular category and for the country of chargeability.