When to start
Question: I'm 15 yeas old and dead convinced that I want to be an author. I want to start seriously writing what will hopefully be a novel. Is it reasonable for me to start writing now?Answer:
Absolutely reasonable. That doesn't mean you will be the next Christopher Paolini. Nor does it mean that your first novel will ever find its way into print. A lot of writers write more than one "practice" novel before they get good enough to publish.
Writing is a talent that gets better with practice. Just like great piano players usually begin as children, the sooner you start writing the better. Your ability to tell a story with words will improve and you will learn a lot in the process.
Besides, writing a novel can be a very enjoyable experience. And some teenagers have published novels (Christopher is just one example.) Your conviction could be right or wrong, but you'll never know unless you start.