I saw one of those "Homes under the Hammer" programs on TV recently.
The guy featured on one program bought his first flat at 19 (with help from his dad). Did it up and sold it, then went off to university.
With the money he got from his flat he bought two more flats and did them both up (while at university) and sold them, bought more flats and so it when on.
The guy was still only 28 and in this program he bought a house in London for £375,000, spent about £125,000 on it (so £500,000 in total).
He split the house into 4 flats and the estate agent valued the 4 flats at about £700,000 in total (£200,000 "profit" !).
So you are never too young to start being a property developer.