Luke consistently presents a pattern of the Baptism in the Holy Spirit being distinct from and subsequent to salvation1. These texts in Acts 1, 2, 8, 9, 11, and 19 form the basis of the Classical Pentecostal "Doctrine of Subsequence." (Subsequence is one of the core distinctives of the Assemblies of God. They address it in the Statement of Fundamental Truths #7.)
- In Acts 1:4,5, Jesus himself, while speaking to those who had trusted in Him as Messiah and Lord, said "Do not leave Jerusalem, but wait there for what my Father promised, which you heard about from me. For John baptized with water, but you will be baptized with the Holy Spirit not many days from now." The Baptism in the Spirit was yet to come for these believers. Drawing the distinction even more clearly between receiving the Spirit and being baptized in the Spirit, prior to this (John 20:22), Jesus breathed on them and said, "Receive the Holy Spirit." Now, He is saying that their Baptism in the Spirit is yet to come.
- Before the first outpouring (Acts 2Acts 2), the 120 are specified as "disciples/believers" (Acts 1:15) and "brethren" (1:16), that is, they were already baptized believers but the Holy Spirit had not come upon them (Acts 1:5, 8) but were now receiving the Spirit.
- As you mention in Acts 8, belief and Spirit Baptism are presented as distinct.
- In Acts 9:17, the believer Ananias calls Paul "brother" before Paul receives the Spirit.
- In Acts 19, the recipients follow Paul's command for water Baptism in Jesus' name (19:5). It is only after this, (vs 6) that the Holy Spirit came upon them.
The Holy Spirit indwells all believers at conversion, but the baptism in the Holy Spirit is shown in Acts and the Epistles to be distinct and subsequent almost all of the time.