We do not guarantee delivery time do to the nature of the Internet and the many variables involved in delivery many messages to many different servers.
In general, when you send a campaign, 80 - 85% of your messages will be sent within the first 10 minutes, and 95% within the first hour. The rest trickle out over the next 30 hours as the server continues to retry sending your mail to receiving servers that are unresponsive. Every hour the server reports on bounces. So within 1-2 hours of sending your campaign you should have a good picture of which emails have bounced and which have been delivered.