Reports on impressions and clicks are usually updated every 15 to 30 minutes. Occasionally there will be a delay of 24 hours or more in the reports that you see on the website. When there's a delay, you'll see this message: "We're sorry, some data in this report is delayed. Please try again later. There's no impact to ad serving or payments."
Please keep in mind that your reports won't show any data for time periods when no page impressions are generated. As a result, you may see a No data available message in your reports.