One of the most important parts of planning to write a document is creating a project calendar. The calendar helps you move through each of the six steps of writing in a timely manner.
Begin by using backward planning. In other words you start with the date that the project (document) is due. Then you build in due dates for each of the steps of writing by going backwards: proofreading, revising, drafting, organizing, researching, etc.
For larger projects you may wish to use a Gantt chart to see how multiple deadlines interact with each other.
If it is a group project then you can use project management software such Asana, Microsoft Project, Clarizen, Wrike, DaPulse, and a host of others to help keep your project on time.
For more information see the chapter on Project Planning.