I can only think of books and manga that have had time skips unless they were memories of the past, but that doesn't count. Or time skips from someone's birth/childhood that only last for an episode or a half of episode. It seems like a difficult thing for animators to do. They have to get used to the new feel of characters and adjust. What about the voice actors? Will they stay the same? If so, that could be a plot hole considering people's voices change due to puberty.