CA Civ Proc Code Section 12c

(a)

Where any law requires an act to be performed no later than a specified number of days before a hearing date, the last day to perform that act shall be determined by counting backward from the hearing date, excluding the day of the hearing as provided by Section 12.

(b)

Any additional days added to the specified number of days because of a particular method of service shall be computed by counting backward from the day determined in accordance with subdivision (a).