You can configure Adobe Reader to automatically return to the 1st page, once you arrived at the end of your document (in Fullscreen mode). Here's how to proceed:
- Click on the Edit menu > Preferences > Fullscreen
- In the right pane, check "Loop after last page"
- Click on OK to validate.
As from now once you arrived at the last page of your document, simplt scroll downward to access the 1st page.