WooCP – Schedule, Reset Countdown Plugin WooCommerce is a fantastic plugin to promote your sale campaigns in WooCommerce. It shows a countdown box with the product on sale, to tell your customer how much time they have left to purchase your product with discount. You can also make it count the time till the up-coming sale period. Addition if you want to countdown display always, you can use Auto Reset Time.

Demo: https://codecanyon.net/item/schedule-reset-countdown-plugin-woocommerce-woocp/25002276