All new employees must complete Section 1 of Form I-9 on or before their first day of employment. Then, within three business days of their start date, they should submit acceptable proof of their identity and eligibility to work in the United States.
As the employer, you should complete Section 2 within those same three business days. If the duration of the job will be fewer than three days, you should complete Section 2 no later than the first day of employment. Section 2 is generally done at the time the employee brings in their identifying documents, as it asks for specific information about these forms of identification.
Answer from Ophelia, SPHR, GPHR, SHRM-SCP:
Ophelia has over 10 years of HR experience supporting clients of all sizes and in virtually all industries. She specializes in coaching clients in feeling more equipped and empowered to manage their teams better. She holds a Bachelor of Arts degree in Sociology and a Masters of Business Administration (MBA) degree with a concentration in Human Resources from Willamette University. A member of SHRM since 2008, Ophelia has been actively serving on the board of directors for the local and regional SHRM chapters for the past five years in multiple capacities.