The 7th chapter of Revelation seems to occur before the last 3 1/2 years. At the beginning of the chapter, the 144,000 are sealed, which happens before the last 3 1/2 years. And in context, the remaining verses speak of those who came out of the great tribulation. If this is referring to the final 3 1/2 years, then this part of the vision will have to happen after the final 3 1/2 years. But it seems more likely to me that this whole chapter takes place before the final 3 1/2 years. Which is correct?
The sealing of the 144,000 on Earth and the heavenly arrival of the Tribulation Martyrs in Rev. 7 will happen before the beginning of the Great Tribulation between the 6th (Rev. 6:12) and 7th (Rev. 8:1) Seal judgments.
Rev. 7:14 threw me for quite a while because in English the verse seems to conflict with the chronological order of the book. Then I did a word study on the Greek version of the phrase, “These are they who have come out of the Great Tribulation” from Rev. 7:14. The phrase “out of” comes from a single Greek word that refers to both the time and place of the event being described. In effect it means they’ll arrive in Heaven before the Great Tribulation begins on Earth, having been removed from both its time and its place.