You can edit your Q-rator posts up to 5-mins before they are scheduled to go out.
To edit a scheduled post, go to the Queue for which the post is scheduled. Learn more about Queues.
Click on Edit Post and make your changes. You can also delete that post by clicking on Delete
To change the time, click on the downward arrow next to Save Post.
Once you're through making changes, click on Save Post.
And you're done!