How to Make a Timeline

"A project plan, according to the Project Management Body of Knowledge, is: "...a formal, approved document used to guide both project execution and project control. The primary uses of the project plan are to document planning assumptions and decisions, facilitate communication among stakeholders, and document approved scope, cost, and schedule baselines. A project plan may be summarized or detailed." ...
The objective of a project plan is to define the approach to be used by the Project team to deliver the intended project management scope of the project.
At a minimum, a project plan answers basic questions about the project:
Why? - What is the problem or value proposition addressed by the project? Why is it being sponsored?
What? - What is the work that will be performed on the project? What are the major products/ deliverables?
Who? - Who will be involved and what will be their responsibilities within the project? How will they be organized?
When? - What is the project timeline and when will particularly meaningful points, referred to as milestones, be complete?" [Project plan. Wikipedia]
The timeline diagram example "New business project plan" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Timeline Diagrams solution from the Management area of ConceptDraw Solution Park.