Upon receipt of such petition, the county board shall examine it to determine whether it complies with the requirements of section 12-910. Upon finding that such petition complies with such requirements, the county board shall set a hearing thereon and cause notice thereof to be published at least three successive weeks in a newspaper of general circulation throughout the area to be included in such proposed district. Such notice shall contain a statement of the information contained in such petition and of the date, time, and place at which such hearing shall be held and that at such hearing proposals may be submitted for the exclusion of land from, or the inclusion of additional land in such proposed district. If the proposed district lies in two or more counties, such hearing shall be held before the combined boards of all counties interested and the time and place thereof shall be as mutually agreed by such boards.