Timescale displayed in Gantt Chart (Bar Chart) has two tiers – the starting date of the week on the top, week day label on the bottom like the one below
You can customize the Timescale to display the number of days left to complete the project. This is how you do it.
Step 1: Double click the Timescale or right click the Timescale and choose Timescale
Step 2: Select Middle Tier tab. In Units drop down select Days and in Label drop down select 4,3, 2, 1, … (From End)