Hi Houston, I'm going to just add my two cents in the interim. I'm sure someone will come along who can explain things much better than I can.
Jesus said we must be born again of the water and spirit
John 3:5
John said Jesus would baptize with the Holy Ghost and with fire
Matthew 3:11
Peter said we are born again by the gospel
1 Peter 1:23-25
According to
Luke 24 the preaching of the gospel began at Jerusalem
The gospel embraces Jesus' death, burial, and resurrection
1 Corinthians 15:1-4 and could not have happened until Jesus died
In
Acts 1:4-8 the disciples asked when the Kingdom of God would come and they were told to wait for the promise of the Holy Ghost
The Kingdom of God is righteousness peace and joy in the HG, so it could not come until the HG was given
Romans 14:17
On the day of Pentecost they were
all filled with the HG and began to speak with other tongues as the Spirit gave them utterance
Acts 2:1-4. This is when the supernatural Kingdom of God was set up upon the earth.
When the gentiles received the Holy Ghost in response to the gospel, they knew it because they heard them speak with tongues
Acts 10:44-46
So speaking in tongues is initial evidence.
There is a difference between the Gift (singular) of the Holy Ghost
Acts 2:38 1 Corinthians 12:13
and the Gifts (plural) of the Spirit
1 Corinthians 12 Romans 12