This is an interesting concept because God is omnipresent, meaning everywhere at the same time. Technically we are already inside of God. You could call that part of God that is in the same place as us the Holy Spirit.
Even though the Holy Spirit is already there, you do not know it. You do not feel it. I believe the reason for this is free will. That gives us a couple more options. The Holy Spirit could enter us the moment we become believers or when we ask for it to enter us. This former was true for me. I remember crying when I was saved. I asked another believer, “Why the tears”. I was told it is the Holy Spirit. The Holy Spirit is strong emotion. Based on that experience I would agree that we receive the Holy Spirit the moment we become believers. The technical term for this is indwelling.
Sylvia Browne says that Mother God is very much like the Holy Spirit in Christianity. That strong emotion in the experience of being saved fits perfectly with that.
Since we established that the Spirit is there as soon as you are saved, do we need to be baptized in water? No, getting baptized in water is a religious ritual. It is more of a symbol and public action of your beliefs. I would much rather be baptized in the Spirit than baptized in water. [Matthew 3:11] Rather than being baptized in water, you should ask to be baptized in the Holy Spirit.
Why should we, “Ask to be baptized in the Holy Spirit”? Even though we are filled with the Holy Spirit at the time of Salvation, that feeling doesn’t last. We get back to the low vibrations of life and loose that feeling. It feels good to be filled with the Holy Spirit. So, we raise our vibration to be filled with the Spirit again. Consciously acknowledging the Holy Spirit is invited in opens to the door to the gifts of the Holy Spirit.
You might also be interested in the post on gifts from the Holy Spirit.