In one of the very old WW comics issues. The woman on the island take there oath to the goddess, get there bracelets, & drink the immortal fountain water at age 19. I don't think that the proper age for any woman to become immortal. Even back than.
With the advances in modern society. What age do you think they would give them all that stuff now a days on the island?
I see that happen around age 27 now a days.
What age do you see the woman of Paradise island taking there oaths?