Acts 17:1-4
Now when they had passed through Amphipolis and Apollonia, they came to Thessalonica, where was a synagogue of the Jews: 2 And Paul, as his manner was, went in unto them, and three sabbath days reasoned with them out of the scriptures, 3 Opening and alleging, that Christ must needs have suffered, and risen again from the dead; and that this Jesus, whom I preach unto you, is Christ.
4 And some of them believed, and consorted with Paul and Silas; and of the devout Greeks a great multitude, and of the chief women not a few.
On 3 sabbath days, Paul went to the synagogue to preach the Messiah, and there were Jews, a great multitude of gentiles, and women there.
Note: Paul went to where the law was taught to preach the gospel, because the law leads to Christ. So far, the gentiles who heard the gospel from Paul were those who went to synagogue on sabbath.