Our Lord's words, for John baptized with water, but you shall be baptized with the Holy Spirit not many days from now, are reminiscent of John the Baptist's statement in John 1:33: "He who sent me to baptize in water said to me, 'He upon whom you see the Spirit descending and remaining upon Him, this is the one who baptizes in the Holy Spirit.' " The promise was to be fulfilled, and the disciples would be baptized with the Holy Spirit, not many days from nowten to be exact. Jesus promised that after He departed, He would send the Spirit (John 16:7).
Despite the claims of many, the apostles' and early disciples' experience is not the norm for believers today. They were given unique enabling of the Holy Spirit for their special duties. They also received the general and common baptism with the Holy Spirit in an uncommon way, subsequent to conversion. All believers since the church began are commanded to be filled with the Spirit (Eph. 5:18) and to walk in the Spirit (Gal. 5:25). Yet these early apostles and believers were told to wait, showing the change that came in the church age. They were in the transitional period associated with the birth of the church. In the present age, baptism by Christ through the agency of the Holy Spirit takes place for all believers at conversion. At that moment, every believer is placed into the body of Christ (1 Cor. 12:13). At that point the Spirit also takes up His permanent residency in the converted person's soul, so there is no such thing as a Christian who does not yet have the Holy Spirit (Rom. 8:9; cf. 1 Cor. 6:19--20).
The baptism with the Holy Spirit is not a special privilege for some believers, nor are believers challenged and exhorted in Scripture to seek it. It is not even their responsibility to prepare for it by praying, pleading, tarrying, or any other means. The passive voice of the verb translated be baptized indicates the baptism by Jesus Christ with the Spirit is entirely a divine activity. It comes, like salvation itself, through grace, not human effort. Titus 3:5--6 says, "He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit, whom He poured out upon us richly through Jesus Christ our Savior." God sovereignly pours out the Holy Spirit on those He saves...
source:
MacArthur Commentaries