From the New York Times:
Florida probably was first sighted by Portuguese navigators, or perhaps by the Cabots sailing from England. Either way, it started appearing on maps as early as 1500. By 1510, its distinctive peninsular shape had emerged clearly on maps in Europe. By 1513, when Ponce de Léon first arrived, so many Europeans had visited Florida that some Indians greeted him in Spanish.
Sounds about right.