How big is too big to start out?
Another two cents worth....
I would encourage someone reasonably young to start out small also. There is just nothing quite like the thrill of learning on a small boat. When you get out on a good breezy day, with the boat heeling as you sail close to the wind...main sheet in one hand and tiller in the other...fighting to keep it right on the edge...feels like you''re traveling about 60 miles an hour (in reality your lucky to be doing 5 or 6).
In short..buy something small to learn on...a few hundred bucks for the learning experience, and you can always buy the big boat later.