Please note that this plugin has only been coded and tested with the Metabox.io plugin (I don’t own ACF and just recently got a copy of ACPT).
This is a simple plugin I created because I needed something that was able to use a custom date/time field (Metabox.io) and turn it into a countdown timer for an events page. You can view a live example of it on two different sites (https://reformed.events and https://thetruelifechurch)


The sites are built with Oxygen Builder and Bricks, respectively. Both pull data from a custom post type and then displayed in a list/grid format by post query which is then populate in each individual event. At the top, the countdown timer is added to the respective single event template and the start date/time is populated and then displayed on how much time is remaining before the event starts. If an event has expired, it displays This Event Has Expired in place of the days, hours, minutes, and seconds.

Please note that this is not an evergreen timer, however it does automatically work if you set the Post type and Field in the settings. The settings for this plugin are located under the main Admin menu -> Settings -> Meta Timer.
**Please note, you may need to save the Post Type first before the Field option populates with the custom fields.

I do plan to add more features (color picker for text and background, and support for other CPT plugins), however this plugin and usage is “As Is” and no support will be provided. This plugin is free, and you are free to modify it but you must attribute back to this post or site.
You can download this plugin here: Countdown Timer Plugin