Highlight the marker track whose marker is to be the reference for the countdown. Following this the properties are displayed in the Properties Table.
Under Locator time check box Display countdown. As an alternative you can also do so the marker track properties dialog. This countdown option can be enabled for several tracks thus including all the markers contained on these tracks in the countdown. Marker tracks with enabled countdown option can be recognized by the orange track ID number in the track head.
When you start playback the timeline time display turns orange and the time is counting down to zero to the next marker. After stopping playback the normal timeline time reappears.
On tab 
Status in the bottom left corner of the program window the time is displayed at a relatively large size, i.e. absolute timeline time in white and countdown time in orange (Advanced License and up). This tab can also be undocked and moved to any desired location as a window. See also Customizing the program window.