I think CC'sMom is right, I wouldn't leave the food on the floor, I would give it to her and give her a certain amount of time, if she doesn't eat it pick it up. I would think eventually she will get the idea.
I have been told that a pup should be ready to do their duty about 45 minutes after they eat. I would try to keep her on a schedule, it will be easier in the long run.
Good luck
Jackie