Your understanding that Peter is saying those present have come from afar off is not accurate. Notice Peter says the stated promise is for those present and their children, AND to ALL that are afar off, After making that point he goes on to say, EVEN as many of God shall call.
Acts 2:39
For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.
If you had just travelled all the way from all the places mentioned in Acts 2 . And you were told the things they were told ,what great joy to hear it was not just for them present , but to their children , their families, their people back home . So we see 8000 Jews and proselytes reached by the 12 from all these places . Wow !
1¶And when the day of Pentecost was fully come, they were all with one accord in one place.
9Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia,
10Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes,
11Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.
12And they were all amazed, and were in doubt, saying one to another, What meaneth this?
14¶But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all
ye that dwell at Jerusalem, be this known unto you, and hearken to my words:
22¶Ye men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the midst of you, as ye yourselves also know:
37¶Now when they heard
this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men
and brethren, what shall we do?
38¶Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
39For the promise is unto you, and to your children, and to all that are afar off,
even as many as the Lord our God shall call.
40¶And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation