I thought Muhammad was on Antigua in 1999, and that he met Malvo on the island at that time, when Malvo was 13 years old. That's what at least one earlier report said.
The 1999 date was a ballpark date reported by the 10/25 Jamaica Observer:
Reporters in Antigua said yesterday that Muhammad lived on the island between 1999 and 2000, apparently having gone there with his three children -- Selena, John and Taliba -- after the break-up of his marriage.
The Washington Post reported on 10/25:
In late March 2000, he picked up the children from school and vanished, according to court records. He later said he took the children to Antigua with their mother's consent.