What is true baptism of the Holy Spirit?

Question: In your book Knowing the Bible 101, you say that Spirit baptism is the way God brings you into the body of Christ (that is, the church), and that you don’t have to ask for it. If this is the case, then how do you explain that Jesus instructed the apostles “to wait for the gift my Father promised” (Acts 1:5), and when the gift arrived (Acts 2:2-4), they were filled with the Holy Spirit, with the evidence of speaking in tongues? I personally, along with many other believers, see the baptism of the Holy Spirit as a separate experience and much to be desired. What is your insight on this?