You give the false impression that Peter was never to preach among the Genitiles.
Peter is referring here at the Council of Jerusalem [circa 50 AD] about the event that happened "a good while ago", meaning at the House of Cornelius [circa 36 AD]. Read what God had to do to change Peter's thinking that the Gentiles should hear the Gospel. Peter had to be pulled kicking and screaming into Cornelius's house, and was clearly stunned at what transpired there, understanding then and only then that the Gospel should also go to the Gentiles, but it was then Paul not Peter who was anointed, prepared, and commissioned with that task:
" . . . they saw that the Gospel of the uncircumcision was committed unto me [Paul], as the Gospel of the circumcision was unto Peter" [Galatians 2:9]
It didn't mean that Peter was limited to only Jews and Paul to only Gentiles, because Gentiles and Jews were often in the same crowds and heard the same messages. But the Gospel as Paul delivered it was specially oriented toward Gentiles, while Peter's always had a unique Jewish flavor.