We started encouraging them to eat by themselves before 1 year old - first start by the snacks, then later with regular meal. It's easier when they go to school because teacher will encourage them to do things themselves. We tried many different encouragement or punishment, like I'll give them candy if finish all; or sticker; or go out after meal; or watch TV. When we train our sons, we usually have a goal and then go little by little to achieve it; perhaps you can encourage them if they eat half or few spoonful by themselves first. And add more and more to receive encouragement. We noticed that boys like to win; you may want to set up some competition between the boys? Like first one finish his rice can have 3 stickers & second place only have 2. They both may try harder to finish faster.