As you can see, the interface for Assistant looks exactly like it does on the Pixel. It can be activated via a simple press-and-hold of the home button on your device. Once you do that, just start saying stuff. It’s pretty handy too, especially with the recent addition of text messaging.
To check and see if you have the Assistant yet, just press and hold your home button. If you see the “New! You just got the Google Assistant” message pop up, you’re set. If not, the feature still has yet to reach you, an outcome not likely to occur at least according to current reports.