This members-only tutorial provides the steps to set up a countdown timer in Oxygen with the value coming from a Date Time Picker type of custom field on an Options page instead of hardcoding the value (like "Nov 23, 2028 00:00:00").
if ( function_exists( 'acf_add_options_page' ) ) {
acf_add_options_page();
}
Go to Custom Fields > Add New.
Create a field group titled say, "Sitewide" having a Date Time Picker-type of custom field with the name of countdown_date. Set it to appear on the Options Page.
Set Display Format and Return Format to F j, Y H:i:s.