Great question @bondar.
Let me address the postscript first. In Numbers 6:1-21 there is a description of a Nazirite, which was a person that took a vow and set themselves apart “to the Lord.” The regulations on how there were to live out that vow are in that passage, a key regulation being to not partake of any products of the vine in any way during the period of their vow.
When the angel tells Zechariah he must not taste wine or strong drink, it’s a similar setting apart like a Nazirite. John has been conceived and consecrated for a purpose and he received the Holy Spirit, even in the womb, to be equipped for the special task ahead.
Although the Spirit is eternal, you are correct that John’s gifting of the Spirit would not have been a common occurrence. In the OT and pre-Pentecost days of the NT the Spirit would enable special gifts on persons being used to usher in and participate with the Kingdom of God. A good example is Simeon and Anna in Luke 2 when Jesus is presented at the temple. How blessed are we that throughout human history God has chosen to use us in His plan for the kingdom!
John the Baptist believed in Jesus as the Son of the Living God. John was saved by his faith.
It is the same for us. We also are saved by faith.
John received the Holy Spirit in the womb. We receive the Holy Spirit when we are born again, or “born of the Spirit” as Jesus says in John 3.
Indeed we are fallible humans with wandering hearts. Although we may not experience the H.S. in the same circumstances as John the Baptist, we can experience the same supernatural guidance in our life. It is the Spirit in us that enables us to be transformed into Christ likeness, but it takes a lifetime of yielding. It is the Spirit that enables us to move from self-centered to God-centered.
Indeed, many stray. We stray because we are not listening to the Spirit, we are not abiding in Christ. We must willingly yield to the changes God desires in us. It will not be forced on us. The process of sanctification, the maturing of our faith, is a partnership with the Spirit where we are the junior partner. But we definitely must do our part.
Are there times in your life where you’ve sensed the moving of the Holy Spirit in your life? John Wesley, who began the Methodist movement, said we cannot even begin to believe in Jesus as our savior without the work of the Spirit–he called it Prevenient Grace. The wooing of our spirit with the Spirit. As this process is prior to our confession of faith, perhaps it’s akin to the Spirit John the Baptist had in-utero.
I’ve often compared how intimately we commune with the Holy Spirit to be similar to tuning in a radio station. At times it’s a weak signal and hard to tune in–often because we are not walking closely with God and living in rebellion (sin). But when we are walking closely with God and being obedient the station can be very strong and easy to tune in.