Hmmm...my first job was working an area farm when I was 14. By 16, I was working 30 hours a week, during the school year, as a cook in a restaurant. By the time I got out of college, it wasn't as much of a transition for me. Very little, in fact.
A couple of my friends never worked a day in their life until they got out of college and the transition was enormous for them. They're both still big screw-ups, come to think of it. Parents, there is a message in this thread in case you didn't already know. A parent's job is to prepare their children for adulthood, not to raise Peter Pans (the kid who never grew up). There is no better way to foster that than WORK. Make 'em get jobs at like seven, they'll be all the more better for it.
On edit: Did I say seven? That's a little young, I was exaggerating a bit.
I should have said ten, make 'em get jobs at ten.