I noticed that Ronaldo scored 8 goals in South American Sub-17 1993: https://pt.wikipedia.org/wiki/Campeonato_Sul-Americano_de_Futebol_Sub-17_de_1993, when he was only 17 years old. The Youtube channel "Mundo Maldini" shows some archived matches with Chile and Colombia: It's a pity that there're few videos we can found on the tournament.