After the mandated waiting period of 72 years, the records of the 1940 U.S. Census of Population are scheduled to be officially released at 9:00 AM on Monday 2 April — today.
Exactly what will be instantly available from the National Archives and what will take a while to be loaded remains to be seen.
Meanwhile, the commercial product Ancestry.com, to which the W&L University Library has a subscription (available to all students, faculty, and staff), is said to be busily loading the records into their database. If you are interested in the names and other records from any particular state(s), you can go to this page and sign up to be notified by e-mail when your states are available.
The Ancestry.com files, when ready, should be much easier to use than the raw NARA form.