California Code, Elections Code - ELEC § 3001

No later than 29 days before the day of the election, the county elections official shall begin mailing the materials required by Section 3010. The county elections official shall have five days to mail a ballot to each active registered voter by the 29th day before the day of the election and five days for each voter who registers to vote after that date. The county elections official shall not discriminate against any region or precinct in the county in choosing which ballots to mail first within the prescribed five-day mailing period.