Any kid, if s/he works hard enough, should definitely be able to reach 1500. It's like middle school diploma. It takes some time and some effort, but nobody should be unable to pass it. As a young kid, s/he is actually better in learning than adults. It's much easier for a kid to reach 1500 in a few year than an adult. A few factors contribute to that conclusion: kids have better memory, more time to study, more time to practice, eager to learn, easier to ask questions, braver to take risk, not fear of losing, and more positive about his/her growth potential.
Now why as quickly as possible? Because, the younger s/he is, the easier for him/her to achieve that. The achievement will provide the best feedback for his/her effort, and propel him/her up to a much higher level no one can imagine.