how and when does one 'receive' the holy spirit?
The Perhaps one of the most misunderstood and debated doctrines of
the Holy Spirit is when He is evident in the Christian's life.
Some Christian sects believe that the Holy Spirit comes upon a person
some time after they have been saved, and that this is evidenced by
special signs (speaking in tongues, etc.), similar to what the early
church experienced at Pentecost.
But this does not appear to be based upon scripture. For example, Paul clearly tells us that the Holy Spirit is 'in' those who are 'in Christ Jesus':
Therefore, there is now no condemnation for those who are in Christ Jesus, because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death...if Christ is in you, your...spirit is alive because of righteousness. And if the Spirit of Him who raised Jesus form the dead is living in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit, who lives in you." Romans 8:1-2,10a,c,11
Clearly, the Spirit of God, the Holy Spirit, is within the person who is in Christ, and is regenerating this person toward sanctification.