I have JUST started working on "Down" with puppy.
He is pretty good on sit, and Down has been added on to that. He has had maybe half a dozen exposures to the word with the action.
The other day I had the Puppy in his crate in the kitchen and I was about to take the two older dogs out to play fetch. They were going nuts because they love going out to play.
I don't want them rushing the door, so I give them a loud, "Down!" Command. They both lay down. The puppy, in his crate, seeing this, lies down too!
Pretty cool to see. He learns from watching, and maybe I can use this to my advantage later.