(I am Mists btw, back to my original name for X-Factor!)
I remember the ASD-trained SALT saying that a main and major purpose of communication is to say what you don't like or want before even saying what you do need.
All of us missed that one when we were asked why humans communicate. It's true isn't it that NT children tend to use "no" before yes.
Anyway, DS (3.5) has been using the phrase, no, not a (whatever we suggest) for a few days now and we're really pleased.
No not a sleep.
No not a nursey rhymes.
No not a nappy change.
No not a Humpty Dumpty.

Now to work on "yes"