When a scheduled event affecting project timelines is delayed, it is crucial for the project manager to communicate this change to all relevant stakeholders. This ensures that everyone is aware of the delay and can adjust their schedules and expectations accordingly. The PMP outlines the importance of clear communication with stakeholders as part of project integration management and stakeholder engagement (PMBOKGuide). References: * Project Management Institute. (2021). A Guide to the Project Management Body of Knowledge (PMBOKGuide) - Seventh Edition. Project Management Institute. * Project Management Institute. (2019). PMP Examination Content Outline. Project Management Institute.