No, you're not mistaken. John the Baptizer (Immerser) was filled with the Spirit from his mother's womb as it says in the Scriptures. That wasn't the same thing, however, as being baptized in the Holy Spirit (born again). As you quoted John saying, the baptism in the Spirit came after Jesus was glorified, that is, resurrected and ascended on high.
“I indeed baptize you with water to repentance. But He who comes after me is mightier than I, whose sandals I am not worthy to carry. He shall baptize you with the Holy Spirit and with fire” (Matthew 3:11 MKJV).
So what's the difference? Christ, as the Son of Man, overcame death, and by His grace, we, the children of faith receive His Spirit and are joined to His resurrection life and power. We are purged by fire and completed in the image of God. This is the salvation John looked forward to, and which Jesus acknowledged by saying:
“For I say to you, Among those who are born of woman there is not a greater prophet than John the Baptist. But he who is least in the Kingdom of God is greater than he” (Luke 7:28 MKJV).
Does this help? Also read The Baptism in the Holy Spirit
After reading your letter, Bill, we edited one of the statements you quoted from our site, in order to make it more accurate. Here's the updated version:
“John recognized that he needed to receive Christ within, the baptism in His Spirit. Until then, John didn't have the mind of Christ, though he was a holy man of God and perfect in his generation. He was inspired by God, knew the Lord and was aligned with Him, but wasn't yet one with Him and sharing His mind as those who receive His Spirit do….”