At what age can my child start tennis coaching?

I'm a tennis player. I've been playing for about 5 years (since I was 9) but never took lessons 'til about 11 months ago. I've gotten so much better! It's amazing what lessons can do, as long as you have a good coach. I recommend starting young but you know, whenever is gr8 too. (Personally, I take lessons 3 days a week,)