In the Publishing Center and under your app, navigate to the Notifications area and select History. This view will display recently sent notifications. In order to read/debug this information there are a few places that you may be interested in.
Target: This can either to going to All devices, or just a a group. The content proofing group will receive an automatic message each time there is new proofing content.
Message: This will display the whole message that was sent.
Created: This displays the time at which the message was created.
Schedule: If the push was scheduled for a particular time and date, it will detail when it was scheduled for. Otherwise if the push went out immediately it will say 'immediate delivery'.
Status: This is either 'in progress' if the push is still getting pushed, or the scheduled date/time has not arrived yet. It will say 'Complete' if the push has finished sending to all registered devices.