Update periods for changes made in DFP
Line item changes, including targeting, creatives, inventory selection, start and end dates, flight dates, impression goals, and pausing or unpausing campaigns can take up to 20 minutes to affect ad serving.
Line item impression delivery will occur within 30 minutes of activation.
Line item impression reporting (and line item status changes from ready to delivering) will occur within 30 minutes.
Network configuration-based changes, including new or edited ad units, placements, native styles, labels, etc., take effect within 60 minutes.
When will an order or line item go live?
A line item's ads will deliver when:
Today falls within the order's flight dates.
The line item competes for an ad call and wins.
Once a line item has started delivering valid, reportable impressions, the status of that line item will change from Ready to Delivering. It's important to note that the line item's status doesn't change as a result of the line item serving impressions that are filtered due to invalid activity.
If the status of your order hasn't yet changed from 'Approved' to 'Delivering,' simply wait a while and check again when you are more certain that the line item has served a valid, reportable impression.