My parents used to feed us cider (around 4% alcohol) with sunday lunch every week - from the age of about 5 or 6. Only one glass, though. We didn't even realise it was alcoholic until much later.

Personally, I think it's a good idea not to reserve alcohol until later, as the discovery is usually a lot more painful - europeans are even better at this, where 12 year olds can appreciate a good wine with a meal.

Hugo