We’ve tried to train our cats to wait for food in approximately 6 months. In the beginning the training was very unstructured and without any idea of what it would work. We called the cats by their names and they knew what was coming – food! However, once this process started the meow would increase to annoying limits until they would get their food.
We started by covering their blows each time they would meow and move towards the food. Off course we got complaints. We would only open the food containers once they would be quiet. That took time and patience! After all, cats have motivations as dogs and people, it is just a matter of finding out what are those motivations and use them towards both parties advantage with respect and gracefully.
Though we trained our cats without previous knowledge, later we found out several sources which explain different approaches. I will emphasize one, which we found to use similar methods to dog training by Barbara Florio Graham, highly recommendable. It has very useful trainings for your cats. I hope you find them worth it.