en_tn/act/11/15.md

General Information:

Here the word "us" refers to Peter, the other apostles, and all of the Jewish believers who had received the Holy Spirit at Pentecost. (See: rc://en/ta/man/jit/figs-exclusive)

As I began to speak to them, the Holy Spirit came on them

This implies that Peter had not finished speaking but had intended to say more.

the Holy Spirit came on them, just as on us in the beginning

Peter leaves out some things to keep the story short. Alternate translation: "the Holy Spirit came on the Gentile believers, just as he came on the Jewish believers at Pentecost" (See: rc://en/ta/man/jit/figs-ellipsis)

in the beginning

Peter is referring to the day of Pentecost.