Hi Charles!

I have tried many practical to give you the best solution so that you can adjust your timestamp as per your choice. Finally I have reached to the point that there are only two best way to make it appear as you want.
1. To appear timestamp as per your choice you have to go to View Option then (View>Reading Pane>Bottom) or if you the message in the table list when the Reading Pane is on the right (View>Reading Pane>Right). This way you can adjust your reading pane. The second way is: if you mouse hover the message in the message list to the left of the Reading Pane. Then you will get one small pop up with the same details. Hope it work for you!