Time Countdown

For products have no variations:

Step 1: From the admin dashboard, navigate to Products > All Products.

Step 2: Select the product you want to set the sale countdown timer for.

Step 3: At the Product data section, choose Product type as Simple product

Step 4: From the tab General, click on Schedule next to the Sale price, set the Sale price as well as the valid time for it.

Step 5: Set some more options right below as you want, then choose the Countdown timer profile.

For products have variations:

At step 3: Select Product type as Variable product

Step 4: Select tab Variations, click on each variation to display the setting

Step 5: Here you will also set the Sale price, valid date and time for the sale, and other settings.

Step 6: Click Save changes after finished editing.