English Standard Version Acts 2:1-4:
1 When the day of Pentecost arrived, they were all together in one place. 2 And suddenly there came from heaven a sound like a mighty rushing wind, and it filled the entire house where they were sitting. 3 And divided tongues as of fire appeared to them and rested on each one of them. 4 And they were all filled with the Holy Spirit and began to speak in other tongues as the Spirit gave them utterance.
Was this the time that the Holy Spirit started to dwell in these believers as in 1 Corinthians 3:16 (ESV):
Do you not know that you are God’s temple and that God’s Spirit dwells in you?