... Don't expect to get much information from Scripture about Christians who are in heaven now because that is not where they are. Heaven is our ultimate destination, but Christians who have died are currently in what is known as the Intermediate State. Evangelical theologian, Wayne Grudem, explains that this is
The state of a person between his or her death and the time that Christ returns to give believers new resurrection bodies. In the intermediate state, believers exist as spirits without physical bodies (Grudem 1999:487).
The souls/spirits of believers go immediately into God's presence (2 Cor 5:8; Phil 1;23).
However, what did Jesus say to the thief on the cross? 'Today you will be with me in Paradise' (Lk 23:43). See also Heb 12:23 where it speaks of 'the spirits of just men made perfect'.
As you state in your reply, the place for the souls of the departed (before man's reconciliation by Jesus Christ) was Paradise or Torment in the heart of the Earth. They were apparently in sight of each other, the just and the unjust. As the description of Lazarus in Abraham's Bosom you have referenced states, the place for the righteous dead was there.
The thief on the cross next to Jesus Christ had a wonderful promise that carried two specific details. First, that his crucifixion would not last days like many others. He would pass from this life that same day (legs were broken.) Second, it was Paradise (Abraham's Bosom) where he would go at his death, and Jesus would go there the same day.
Having that picture of the thief being in Paradise, and of Lazarus being in Paradise (Abraham's Bosom,) and that of souls being in the heart of the Earth, we can see that Jesus went there like all others who died from Adam to the Resurrection of our LORD Jesus. As stated in scripture, there was a death sentence upon all people because of the sin of Adam, and there was no way made into the presence of God the Father.
Jesus made a reconciliation between Man and God, and made a way for man to be ushered into His presence. He went to the Father after first going into the heart of the Earth for three days and three nights.
I Peter 3
18 ¶ For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:
19 By which also he went and preached unto the spirits in prison;
Matthew 12
40 For as Jonas was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth.
John 16
16 ¶ A little while, and ye shall not see me: and again, a little while, and ye shall see me, because I go to the Father.
17 Then said some of his disciples among themselves, What is this that he saith unto us, A little while, and ye shall not see me: and again, a little while, and ye shall see me: and, Because I go to the Father?
--- etc.---
28 ¶ I came forth from the Father, and am come into the world: again, I leave the world, and go to the Father.
John 20
17 Jesus saith unto her, Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and to my God, and your God.
As Jesus Christ had victory over Death, Hell and the Grave, He imparted that victory to those righteous people who were kept in Paradise (Abraham's Bosom,) and led them into the abode of God, Heaven, God's Throne, when He ascended after His Resurrection. That aspect is covered less by scripture (as noted by you, OZ,) but we are told plainly that it happened.
Jesus Christ said that, upon their deaths, His followers would ever be with Him, where He is. Presently that is sitting on the throne of God the Father, at His right hand, and in the future, it will be returning in glory, reigning on Earth, and eventually, inhabiting the Great, Holy City, New Jerusalem on the New Earth.
Psalm 68
18 Thou hast ascended on high, thou hast led captivity captive: thou hast received gifts for men; yea, for the rebellious also, that the LORD God might dwell among them.
Ephesians 4
8 Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men.
9 (Now that he ascended, what is it but that he also descended first into the lower parts of the earth?
10 He that descended is the same also that ascended up far above all heavens, that he might fill all things.)
... At that time, the understanding of going to be in Paradise was not unconscious existence, but a place of conscious existence (see also Lk 16:19-31). Paul said his desire was 'to depart and be with Christ' and that was 'far better' (Phil 1:23).
In the story of Lazarus (not referred to as a parable,) Jesus states that the dead were aware, the dead prayed for the living, and that there was no mercy for the unjust in torment there. Abraham told "the rich man" that, his brethren had Moses and the prophets, and they should hear them. They would not respond if a man returned from the dead. The "rich man" replied that a person coming back to life from the dead may be just what they needed.
Lazarus actually did come back to life after 4 days in the grave. This was an answer to the prayer of a dead person for people living on Earth. The Gospel of John indicates it had the effect of causing many to believe in Jesus Christ, and that bothered the religious leaders enough to consider having Lazarus killed in addition to their plans to kill Jesus.
(John.12:10-11)
We are promised by the LORD that we will ever be with Him when we are no longer in this life. (II.Cor.5:6-8) Absent any clear scripture stating that there is some intermediate place of existence, since the souls of the righteous dead were take captive when Jesus ascended, we are left with this fact, that the righteous dead of our age of grace are ushered into God's presence at their death. Paul clearly stated that if he were to die, it would be better for him, but not for those who would count on him writing letters of spiritual instruction and admonition.
(Philippians.1:21-15)
There is much encouragement in the later letters of Paul, as the LORD prepared him to depart this life, and be with Him in Heaven. We can see the value of Paul not being allowed to leave this life when he was stoned at Lystra, or nearly pulled into pieces in Jerusalem. We benefit as we see the truth of the scriptures related to us by the Apostle Paul, and those here at that time may not have been able to endure without that being imparted to them.
.