Unless the parties shall have lived separate and apart from each other for a period of twelve (12) months next before the filing of the complaint or unless the defendant is constructively summoned by publication of warning order, no decree of absolute divorce or of divorce from bed and board shall be rendered in any action brought on any grounds except bigamy before the thirtieth day following the day upon which the action for divorce is commenced. This prohibition is not subject to waiver by either or both parties to the action for divorce. However, the parties may agree that the case may be submitted in vacation.