We have two pups and Brooke is a chow hound while Ben prefers to take his time. Brooke has been taught that she cannot touch Ben's dish until he walks away from it.
However, there are times when he doesn't want to eat his food, so he has only a couple of minutes to start eating it. If hfe has not touched it by the time Brooke is finished, it gets picked up. He is given another opportunity at lunch and if he doesn't want it then, he waits until dinner (btw fresh food). It's rare that he will actually wait until dinner, but he has. He will eat when he's hungry.
Dogs will not starve themselves and she will quickly learn that free feeding is over.