It takes a long time to download those big AAA titles, so I'm afraid you are in for a wait. The Division is, what...30-40GB. 8 hours sounds like it's in the ballpark for a download, depending on how fast your connection is and how slow Sony's servers are at the moment.
Keep in mind that you can set your PS4 to turn off after the download is complete. Just push the PS button on your controller, and it should give you that option.