One of the advantages of Cinematic Virtual Reality over traditional movies is that viewers can freely explore the virtual space. However, such freedom leads to a problem of missing some key events during watching. Therefore, directional visual guidance in the virtual space is vital for the viewer to follow the storyline and capture key events. Generating moving objects is one of the most commonly used diegetic guidance techniques which can implicitly guide the viewer's attention in the virtual space. In this paper, we investigate the formulation of key events in Cinematic Virtual Reality with event-of-interest script. Based on the formulation, we analyze the factors influencing diegetic guidance and propose an automatic-generating approach named Dynamic Diegetic Guidance. User study showed Dynamic Diegetic Guidance has a higher degree of immersion and takes less time to redirect viewers to key events compared with fixed guidance techniques, which makes the viewing experience more informative and entertaining.