The answer to this question depends on a few factors.
The apostle Paul wrote in Philippians 1:22-23, “But if I am to live on in the flesh, this will mean fruitful labor for me; and I do not know which to choose. But I am hard-pressed from both directions, having the desire to depart and be with Christ, for that is very much better.” Charles Spurgeon said of this passage, “He said he had a desire to depart, and the desire was a strong one. The Greek word has much force in it. He panteth, he longeth to be gone.”
Based on Paul’s words to the Philippian church, it is fair to say that he had a desire to depart this world and be with Jesus because “to live is Christ and to die is gain” (Philippians 1:21b). Paul’s desire to be with Jesus was not sinful because he did not focus or dwell on it. Instead, he was determined to fulfill the ministry Jesus called him to accomplish (Philippians 1:24-26). However, if Paul were to stop accomplishing his God-ordained calling and focus his time and attention on going to Heaven—that would be problematic and sinful.
The Bible does not teach anyone to stop “living” so they can focus on Heaven, even though death is “a gain” for born-again believers. Instead, it says we should love God and others and become more like Jesus Christ. The Scriptures also direct us to “seek first the Kingdom of God and His righteousness” (Matthew 6:33) and “pursue righteousness, faith, love, and peace, with those who call on the Lord from a pure heart” (2 Timothy 2:22).
Yes, Heaven will be an unimaginable blessing and well worth the wait. It is also something we should look forward to as Christians. But Paul warns against being idle in 2 Thessalonians 3:6-15, which would apply to anyone being unproductive on Earth and preoccupied with Heaven. Therefore, we should be about our Father’s business until Jesus returns or takes us to Heaven—whichever comes first.
I hope this information helps answer this valid question.