Both John the Baptist and Jesus prophesied the church age, when believers would be baptized with the Holy Spirit.
The baptism of the Holy Spirit came on the day of Pentecost, but it was not only for these few individuals. Peter said in Acts 2:39, "For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call." This same power is available to all believers right now.
The promise of the Spirit being poured out on "all flesh" is speaking of all manners of flesh or mankind. It is evident that not everyone has the Holy Spirit. This reveals that the door of salvation and the filling of the Holy Spirit is opened unto Jew and Gentile, male and female, adult, and child.
Many people argue whether or not we are in the last days. Joel prophesied that this outpouring of the Holy Spirit would take place in the last days and Peter said that was what happened here, on the day of Pentecost.
If the coming of the Holy Spirit on the day of Pentecost, which happened nearly 2,000 years ago, was the beginning of the last days, then the time must certainly be getting short for us. This should settle the argument for those who believe the Bible.
We can confidently say that this is our last generation. We need to be about our Father's work.