Run line items at given hours or days (dayparting)
With day and time targeting, you can set your line items to run only during specific hours or days, or as little as 15 minutes per week. For example, you might set line items to run only on Tuesdays, or from 3 to 6 pm daily.
To set day and time targeting for a line item:
Click the Orders tab, then click the appropriate order.
Create a line item or click a line item you'd like to edit.
Under "Adjust delivery," click edit next to Day and time.
Select your day and time settings.
Choose whether to use the publisher's time zone or the user's time zone.
If you use the user's time zone, reports might show impressions being delivered at untargeted hours. That's because reports show all impressions in the publisher's time zone. For example, if the publisher is based in London but is targeting New York and the user's time zone from 3 pm to 6 pm, reports will show impressions being delivered from 9 pm to midnight, because London is six hours later than New York.
Click OK, then Save.
Before you choose your day and time settings, you may wish to run an hourly report to see what times of the day your ads receive the most valuable traffic.
Your ads will stop serving impressions according to the schedule you set. However, click reporting can be delayed. You may notice recorded clicks for up to an hour after a scheduled period ends. Rest assured that these clicks aren't errors, and have only occurred during the period you scheduled.
When you run a forecast for a line item, the forecasting simulation takes into account the time period during which line item is eligible to serve and the amount of traffic expected during that time period; it then distributes those impressions based on the forecasting sample file, which accounts for the previous 28 days of traffic.