At salvation a very important ministry of the Holy Spirit took place in your life. But that ministry is different from the Baptism in the Holy Spirit.
In the moment you made Jesus the Lord of your life, spiritual death was removed from your spirit, and there was born in you a new life, a new spirit. You were literally born of God. “Dear friends, we are already God’s children” (1 John 3:2). “Everyone who believes that Jesus is the Christ has become a child of God” (1 John 5:1). Without encountering the Holy Spirit, man cannot be born again (Romans 8:9).
After you become a new creation, however, it is God’s will that you be baptized in the Holy Spirit with the evidence of speaking with other tongues (Acts 2:4, 19:2-6). This is a separate experience the Father desires for you (Luke 11:13). Receiving the Baptism in the Holy Spirit is important to a Christian because of the many ways He enables you to be victorious in your life. He’s there to help you!
Source: Kenneth Copeland Ministries.