The USCIS has issued guidance to users of its eVerify system with regard to the "hire date" for new employees.  If the E-Verify record was created before the employee began working for pay, the E-Verify hire date is the date the case was created in E-Verify; if the E-Verify record was created on or after the employee began working for pay, the E-Verify hire date is the date the employee began working for pay.  Employers working under federal contracts containing the FAR E-Verify clause and are creating E-Verify records for existing employees must use the original dates those employees began working for pay, even if completing new I-9 forms.  The USCIS guidance can be found here.