prior warning/notice
From Longman Dictionary of Contemporary Englishprior warning/noticeprior warning/noticeBEFOREa warning or announcement made before something happens The society must give customers prior notice before changing the cost. The bomb exploded without any prior warning. → priorExamples from the Corpuswithout ... prior warning• Note: Don't ever send an attachment of more than a few hundred kilobytes without prior warning or agreement.