In the Activation and Preview tab, specify a start and end date for your Product Recommendations campaign, select days of the week to run the campaign, and preview the campaign using a product or category.
When a campaign is ready, click Save campaign and return to the Campaigns tab. New campaigns are inactive by default, so find your campaign and click Play to activate it. You can pause/deactivate a campaign in the same way. Changes are applied immediately to your site.