California Code, Health and Safety Code - HSC § 13819

A petition may consist of a single instrument or separate counterparts. The chief petitioner or petitioners shall file the petition, including all counterparts, with the executive officer of the local agency formation commission of the principal county. The executive officer shall not accept a petition for filing unless the signatures have been secured within six months of the date on which the first signature was obtained and the chief petitioner or petitioners submitted the petition to the executive officer for filing within 60 days after the last signature was obtained.