Timelines allow you to set proper expectations, set a schedule, and track to success. Below is a sample timeline that can be used to organize your prospect and align to their implementation date and your/their buying process. Oftentimes buyers need their buying vision shaped, and the below sample can help that.

A timeline like the above, will set proper expectations and allow you and your prospect to track progress throughout the sale/buying cycle. Gives your prospect the ability to tell you the steps that need to be visited, reworked, or skipped. Gives you the ability to manage your time appropriately and report your deals accurately to management for forecasting.
This is the type of document that should be revisited on each check in call with your prospect, as well as with your internal team during prep sessions. It allows for focused conversations as well as tracking towards a successful deal won and implementation timeline.
Use this document early prior to evaluations occurring to hold your prospect accountable and continue to reference this document over and over again.
TLDR
Using a timeline to track the evaluation process, procurement, and sign on date helps keep all parties aligned and keeps your prospect accountable