California Code, Elections Code - ELEC § 11222

(a) The petition shall be filed by the proponents, or by any person or persons authorized, in writing, by a proponent.  All sections of the petition shall be filed at the same time.

(b) When the petition is presented for filing, the elections official shall determine the total number of signatures affixed to the petition.  If, from this examination, the elections official determines that the number of signatures, prima facie, equals or is in excess of the minimum number of signatures required, the elections official shall accept the petition for filing.  The petition shall be deemed as filed on that date.  A section of the petition not so filed is void for all purposes.  If, from the elections official's examination, the elections official determines that the number of signatures, prima facie, does not equal or exceed the minimum number of signatures required, the official shall not take further action.