What?
The Comforter , and perhaps which what is rather who...
Who is also alluded to in Lamentations'1' want of:16For these things I weep; my eyes flow with tears. For there is no one nearby to comfort me, no one to revive my soul. My children are destitute because the enemy has prevailed.
And Who is promised by Jesus in John 15:26When the Advocate comes, whom I will send to you from the Father—the Spirit of truth who proceeds from the Father—He will testify about Me
When?
You believe without seeing, which may be talking about understanding rather than visualization (it is after being baptized that you will 'see', "know,' 'understand').
Acts 10:44 While Peter was still speaking these words, the Holy Spirit fell upon all who heard his message.
Acts 11: 15 As I began to speak, the Holy Spirit fell upon them, just as He had fallen upon us at the beginning.
Acts 15:8 And God, who knows the heart, showed His approval by giving the Holy Spirit to them, just as He did to us.
Where?
With your spirit
Romans 8:15 For you did not receive a spirit of slavery that returns you to fear, but you received the Spirit of sonship, by whom we cry, “Abba! Father!”
Romans 8:16 The Spirit Himself testifies with our spirit that we are God’s children.