Upon receipt of a petition in the form described in Sections 26550.5, 26551, and 26553, the clerk of the legislative body shall place such petition on the agenda for the regular meeting of the legislative body next following the clerk’s determination that such petition is substantially in the form described in Sections 26551 and 26552 and upon verification that the signatures affixed to the petition represent owners of not less than 10 percent of the real property to be included within the proposed district.