The project manager should prioritize and estimate the milestones for the high-level requirements based on historical data, as this is a way to initiate the project planning process and align the project with the program objectives. The project manager should also use progressive elaboration and rolling wave planning techniques to refine the project scope, schedule, and cost as more information becomes available from the other projects within the program. The project manager should not escalate to the management team to increase the timeline (choice A), as this would imply that the project manager is not able to manage the project uncertainty and complexity. The project manager should not wait for the other project estimates before planning the schedule (choice B), as this would delay the project initiation and execution, and create dependencies on external factors. The project manager should not ask the PMO to estimate the tasks for all the projects and share the project management plan (choice D), as this would undermine the project manager’s authority and responsibility, and create confusion and inconsistency among the project teams and stakeholders. References:

PMBOK Guide, 6th edition, page 17: “Projects within a program are related through the common outcome or collective capability. If the projects are not interdependent or mutually supportive, they may not belong in the program.”

PMBOK Guide, 6th edition, page 18: “Program management focuses on the project interdependencies and helps to determine the optimal approach for managing them.”

PMBOK Guide, 6th edition, page 176: “Progressive elaboration involves continuously improving and detailing a plan as more detailed and specific information and more accurate estimates become available.”

PMBOK Guide, 6th edition, page 177: “Rolling wave planning is an iterative planning technique in which the work to be accomplished in the near term is planned in detail, while the work in the future is planned at a higher level.”