The best course of action for a project manager who is experienced in both predictive and adaptive approaches, when dealing with stakeholders familiar mostly with predictive projects, is to first understand the scope complexity and project magnitude. This initial step is crucial as it helps in determining the most suitable approach for the project at hand. A hybrid approach may be beneficial in some cases, but without a clear understanding of the project's demands and challenges, it's premature to decide on the methodology. The project manager should assess the project's needs, evaluate the stakeholders' familiarity with different methodologies, and consider the potential need for training if an adaptive approach is chosen. This approach aligns with the PMI's guidance on tailoring the project management approach to the unique aspects of the project and the environment in which it operates.
References: (Based on the PMI's principles of tailoring the project management approach to the project's characteristics and the stakeholders' expertise.)