Note 1 at Ac 19:1: These twelve men (Ac 19:7) were born again (see note 2 at Joh 3:3 and note 5 at Joh 3:7). Otherwise, they would not have been called disciples (see note 8 at Joh 8:31). It was certain that they were not the Pharisees' or anyone else's disciples except the disciples of Jesus, or else Paul would not have asked them if they had received the Holy Ghost since they had believed. He would have known that people cannot receive the baptism of the Holy Ghost until they have first believed on Jesus (see note 27 at Joh 14:17).

Therefore, these men had believed (Ac 19:2) in Jesus, but they were not operating in the power of the Spirit that came through the baptism of the Holy Spirit (Ac 19:2, see note 1 at Ac 18:24). This shows that Christians can be born again without having the baptism of the Holy Spirit. The baptism of the Holy Spirit is a separate experience from being born again (see note 6 at Ac 2:4).

They heard about the Spirit baptism, believed, were re-baptized in water in the name of the Lord Jesus (Ac 19:5), and then immediately received the baptism of the Holy Ghost with gifts of the Holy Spirit evident (Ac 19:6). This proves that there does not have to be a waiting period or tarrying for the Holy Ghost (see note 4 at Lu 24:49).