After the plan of conversion has been approved by the commissioner, the society shall mail notice by registered or certified mail to all of its subordinate lodges or branches, by whatever name called, stating that a proposal will be made at a meeting of the supreme governing or legislative body of the society, to be held at least 90 days after the mailing of the notice, to convert the society into a stock or mutual life insurer and enclosing a copy of the proposed plan of conversion.