Williams is currently without a team principal or technical director after the winter departures of Jost Capito and FX Demaison.
AlphaTauri had previously been poised to become the first team to complete a launch event when revealing the livery of the AT04 on February 11 in New York.
Although the majority of teams often use at least one of their two permitted filming days to complete a shakedown of the new machinery, the first proper running will be completed when pre-season testing begins in Bahrain on February 23.
At the same venue just one week later, the season will begin in earnest with the Bahrain Grand Prix.