Paul does not say in this text that he will go to be with Christ when he dies. He undoubtedly was using the word "depart" in reference to his death. But the Bible clearly reveals that Paul did not believe his "departure" would mean immediate entrance into heaven. Here's the proof: "The time of my departure is at hand. I have fought a good fight, I have finished my course, I have kept the faith: Henceforth there is laid up for me a crown of righteousness, which the Lord, the righteous judge, shall give me at that day; and not to me only, but unto all them also that love his appearing." 2 Timothy 4:6-8.
Since Paul obviously did not expect to get his eternal crown at his departure in death, when was it that he anticipated actually being with Christ? "For the Lord himself shall descend from heaven ... and so shall we ever be with the Lord." 1 Thessalonians 4:16, 17. There it is. Paul's desire to depart and be with Christ involved the resurrection that would take place at the end of the world. Since the unconscious sleep of death is like a moment, Paul speaks of death and the coming of Christ as almost simultaneous. And so it will seem to those who depart and awake from death to see Jesus coming.