All the disciples of Jesus were baptized and immersed in the Holy Spirit at Pentecost. This is not Pentecost. This is just the 11 apostles. This breathing in of the Holy Spirit would carry them through to Pentecost. It occurred after the resurrection of Jesus and before His ascension.
And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit.
English Standard Version (Wheaton, IL: Crossway Bibles, 2016), John 20:22
Jesus came to them and reassured them; but He also enabled them through the Holy Spirit. John 20:22 reminds us of Genesis 2:7 when God breathed life into the first man. In both Hebrew and Greek, the word for “breath” also means “spirit.”
Here is a literal translation by Robert Gundry:
Therefore, Jesus said to them again, “Peace to you. Just as the Father sent me, I too am sending you.” 22 And on saying this, he breathed into [them] and tells them, “Receive the Holy Spirit. 23 Whosesoever sins you forgive, they’re forgiven for them. Whosesoever [sins] you retain, they’re retained.”
Source: Robert H. Gundry, Commentary on the New Testament: Verse-by-Verse Explanations with a Literal Translation (Peabody, MA: Hendrickson Publishers, 2010), 458.
The breath of God in the first creation meant physical life, and the breath of Jesus the Messiah in the new creation meant spiritual life. The believers would receive the baptism of the Spirit at Pentecost and be empowered for ministry. Apart from the filling of the Spirit, they could not go forth to witness effectively. The Spirit had dwelt with them in the person of the Messiah, but now the Spirit would be in them.
Source: Warren W. Wiersbe, The Bible Exposition Commentary, vol. 1 (Wheaton, IL: Victor Books, 1996), 393.