Asynchronous (adj.) not occurring at the same time
Government schools decide what all students are supposed to do at any point in time. This, of course, is not at all appropriate for gifted children. Fortunately, you can homeschool!
Embrace asynchronous development. It is OK if your student has 1st grade reading skills, 8th grade math skills, genius music skills, and the social skills of a rock. Start where they are in each area and move forward, even if it is just a toe length. Also expect quantum leaps--kids don't learn in neat, straight lines according to the lesson plan in your teacher's edition.