iOS 8 Update - Any Interaction Needed?

I'm thinking about leaving my 5S home to update while I go out for dinner shortly and I'm wondering if there is any interaction needed on my behalf once the update process begins?

Can I start the update and come home with (hopefully) the update done and the phone restarted and ready to go? Or will it require some sort of action on my part? I can't remember the process when I updated to 7.0 last year.

I don't want to leave it home for one or two hours and come back to find out it didn't even start yet because it was waiting for me to ackowledge something.

 

As long as the actions are only needed at the end of the process that's fine, I was worried something would hang up before it starts and I'd come home to a process that never even started. Thanks for the info.