Once you have a post queued or scheduled, you may want to edit when that post is supposed to be shared, or cancel it altogether.
From My Shares
1. Click 'My Shares' at the top of your screen.
2. Click 'Queue' to see your queued and scheduled posts
3. Click on a queued post whose queue time you would like to edit
4. Edit the scheduled queue time for each social network and click save or delete the scheduled post.