Don't allow time to be entered on a project/task before the Start Date

[#1]

Description - Do not allow time to be entered on a project or task before the Start Date (planned or actual)

Why is this feature important to you - better compliance when it comes to entering time/timesheets and in the end give more accurate reporting. Currently our team is using Workfront for time/timesheets so it is important to be as accurate as possible. 

How would you like the feature to work - When a user goes to enter time on a project or task, the days before the start date of the object are greyed out, not allowing them to enter time in the past or before the object was created. Helpful if this could be an option in the Setup menu. 

Current Behavior - The user can enter time in the past for a project or task that was just created, giving inaccurate data on Timesheets and in reporting.