Template:Signpost/DateCountdown/doc

For this:

Utility template for Signpost/Deadline. Displays a horizontal "progress" bar representing the amount of time remaining in a time span, color-coded (green → yellow → red) to indicate how close it is to the end of the span.

The bar is overlaid with various pieces of information:
 * an optional text label
 * an offsite link to convert the displayed UTC time to local timezones
 * and, if short is not enabled:
 * the proximity to the end date expressed in number of days "left", or "ago" (for past dates)
 * the percentage value of the time remaining

Parameters

 * YYYY-MM-DD: The start of the span.
 * YYYY-MM-DD HH:NN UTC: The end of the span. (Optional time values default to 00:00 UTC.)
 * text: Optional text label to precede the end date, when labeling the bar.
 * truthy value: If set, disables the days left/ago labeling and the percentage display.
 * number or percentage: Optional CSS width for the bar, defaults to 100%. Values followed by a percent sign are interpreted as percentages, all others in pixel (px) units.

Example
How much remains of the current calendar month: