The charter commissioners shall propose a charter for the government of the City-County of Sacramento. The charter so prepared shall be signed by a majority of the charter commissioners and shall be filed in the office of the clerk of the largest city and in the office of the county clerk. The legislative body of the county shall, within 15 days after such filing, cause such charter to be published once in a newspaper of general circulation printed and published in the county and in each edition thereof, during the day of publication.