Start dates tell your team members when things should begin.
It sounds obvious, but many teams manage by due date alone. It is even embedded into some project management software -due date only, no start date.
If a team member only has a due date, they are always playing catch-up. Project managers will only know when the milestone is late. Communication becomes all about getting status updates. People will perpetually be scrambling to keep up with what’s on their plate.
What’s more, planning becomes a matter of staggering milestones based instead of making strategic and informed decisions. Prioritizing milestones and juggling fires becomes the main mode of operation. Discussion is limited to “what are you working on? how is it going? can you squeeze one more thing in?”
Adding in a start date, along with an end date, gives people a sense of how long the milestone should take. It also gives them a sense of how long they have to complete it, compared to other milestones on their plate.
This allows you to plan work, strategically. It also allows you compare your estimates of how long you thought a milestone would take against how long it actually did take. You can then change that the next time somebody needs to do the same thing. You and the organization can learn from past experience.
Here’s another reason to use start dates. It impacts your bottom line. Since many companies bill clients based on the duration of a task, I’ve seen client’s double their revenue and increase profitability by starting to keep track of start and end dates.