65 ILCS 5/7-2-7

The day of the first election of officers of the united city shall be the next regular election date at which municipal officers are scheduled to be elected as provided in the general election law, occurring not less than 90 days after the proclamation of the union or, if a municipal primary is required, not less than 150 days thereafter. The regular general municipal election shall occur thereafter at the time provided in the general election law.