Oh OK. The disciples were all already baptized into Jesus. Being baptized into Jesus name was introduced to non-disciples at Pentecost.
The upper room was where Peter and the other 10 disciples stayed. There's no way 120 people were staying in one room together. The house that they were gathered in when the spirit fell on them and Jews from every nation were gathered together was the house of God, ie, the temple. You can read about this starting at the bottom of page 122 in this book.
The Hope of Israel. What is it?
https://www.brethrenarchive.org/media/366039/mauro-p-_-the-hope-of-israel.pdf
First, I know that GOD uses others through the Holy Ghost to explain HIS word in more detail since HIS word does not show us everything in detail.
But those doing so, will have to use scripture backing up their thoughts.
If you know the book your referring to, I see the link but I don't follow links or men with their opinions.
If what he says can be backed up with HIS word, share what it says please.
This is what I know,
JESUS promised the first message to be preached in Jerusalem.
Luke 24:47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
This was that first message.
Acts 2:38-39
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.
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.
So in Acts 2:38 was the fist time being baptized in JESUS name.
So tell me if they were not all baptized in JESUS name at that point when were they using HIS word please.
Some problems with you statement.
1.
Acts 1:13 And when they were come in, they went up into an upper room, where abode both Peter, and James, and John, and Andrew, Philip, and Thomas, Bartholomew, and Matthew, James the son of Alphaeus, and Simon Zelotes, and Judas the brother of James.
14 These all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with his brethren.
15 And in those days Peter stood up in the midst of the disciples, and said, (the number of names together were about an hundred and twenty,)
HIS word say, there was 120 in the same room.
2.
It does not say Jews from every nation until after they were filled.
After verse 4, the story continues.
Acts 2:5 And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven.
6 Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language.
I don't have to be right about anything, thank you GOD BLESS.