You can now schedule push messages for sending at a later date and time. The push message form has the same schedule selections as the email broadcast form now.

On the app notification broadcast form, set the option under Schedule Message Delivery to "Schedule Message for Sending Later". Then use the date and time fields to set date/time the message will be sent. The message will be saved into the broadcast history list with the send date/time showing. When that date/time comes the message will be sent.