Trying to propagate the status of a project

Hello! I need help with a timeline project I am working on. I am pretty basic in excel, but can follow instructions and usually fumble my way to success! I'm struggling on this one though and would really appreciate any help! I'm trying to figure out how to propagate the status column, by writing a script/equation between the date completed and the estimated completion date. My columns/rows are as shown below. I need help on the how to do it? Also, is it possible (and if so how) to add a visual versus written status like completed/not completed?

Milestones/Required Action Estimated Completion Date Date Completed Status
Demo of Web 11/18/2016 11/30/2016

Once I get the status to propagate, my ultimate goal is to have an additional tab with a slicer that shows just the milestone and the status. Thanks in advance for any help!!!