This is not a sign of an immediate heaven.
This is simply your opinion of the scripture.
It's not just my opinion, it is my interpretation based on the Scripture itself. If this is your response then every single discussion on this forum is folly as we are just presenting our opinions about Scripture.
The fact is, we have to make observations, and then provide interpretations that best fit those observations. Your interpretation clearly did not fit the context, which I demonstrated to be about Paul's tension of remaining in the flesh, and departing to be with Christ.
Remove the idea of "heaven," and just think about what it is actually saying. Paul thought dying was gain because when he departed this life, he would go to be with Christ.
That is not only the historical interpretation of the passage, but it is exegetically demonstrable as I just showed.
Since the dead right now are not aware of time, to them it will be immediate.
Paul fully understood the first resurrection and the politics of it.
1 Cor 15.
That would be a possible explanation, but it doesn't reconcile all the texts on the matter.
Jesus statement to the thief that they would be together in Paradise that very day. (Luke 23:43)
The great cloud of witnesses being the OT saints watching our journey of faith. (Hebrews 12:1)
"The assembly of the firstborn who are enrolled in heaven" ... "the spirits of the righteous made perfect." (Hebrews 12:23)
Again, I don't see any reason why a person would deny that Christians continue to live on directly after dying. The resurrection is paramount and primary, but to depart from the flesh and be with Christ is a great gain.
22 For as in Adam all die, so also in Christ shall all be made alive. 23 But each in his own order: Christ the firstfruits, then at his coming those who belong to Christ. 24 Then comes the end, when he delivers the kingdom to God the Father after destroying every rule and every authority and power.
Yes, I also embrace and place central (as does the NT) that the resurrection is primary. The intermediate state is hardly mentioned, and God wants us to put our hope in the New Creation, the restoration of all things. Yet, this does not mean that we will be apart from him for all that time.
I believe that Paul is with Christ now, that departing from this world meant deeper union with Christ, and I think he has achieved this.