There is no specific age to start masterbating. Start when you want to. =)
And truthfully... It is gross when you think about it. But so is sex. =P Sex and pleasure are a natural instinct. So, fly at 'er.
Just be careful, because somethings can cause an infection, so keep everything you use clean. =)
A LARGE majority of people masterbate there is no "normal" age to start. Just make sure your nails are trimmed and your hands are clean =]How do girls masturbate?