A.R.
When they start throwing food/dropping food/ playing with food - the meal is over and the plate should be removed. They won't starve, I promise!
Wish I had started this consistently when mine were littler. I still have issues with my 3 year old blowing milk bubbles, playing in her plate, etc because I wasn't firm enough when she was little. Now she's learning that if she plays with her food Mommy assumes she's done and takes the plate away, but it's a much harder lesson for all of us at this age.