At the end of a third planning meeting, the client and a functional manager requested...

 The project manager should explain that more features can be planned in upcoming iterations and begin building the product12. This approach aligns with the principles of Agile project management, which emphasizes iterative development and the delivery of incremental value12. By starting the build phase, the team can start delivering value and receiving feedback, which can inform the planning and development of additional features in future iterations12. This approach also helps to prevent scope creep, which can delay the project and increase costs3. References: 

https://www.projectpractical.com/12-steps-to-initiate-and-plan-a-successful-project/ https://asana.com/resources/project-initiation