Actually, the angel in Rev 14:6, 7 is preaching the gospel during God's great wrath, not before. New tribes are continually being found and preached to even as I type this and many that are preaching to them first have to build up a confidence with them so they will welcome the preachers into their villages. Although traveling to these villages is usually by foot going through jungles as you can not drive there many do die a martyr's death within the jungles before they even reach the villages as they are heavily protected from outsiders.
6Then I saw another angel flying in midair, and he had the eternal gospel to proclaim to those who live on the earth—to every nation, tribe, language and people. 7He said in a loud voice, “Fear God and give him glory, because the hour of his judgment has come. Worship him who made the heavens, the earth, the sea and the springs of water.”
8A second angel followed and said, “ ‘Fallen! Fallen is Babylon the Great,’a which made all the nations drink the maddening wine of her adulteries.”
9A third angel followed them and said in a loud voice: “If anyone worships the beast and its image and receives its mark on their forehead or on their hand, 10they, too, will drink the wine of God’s fury, which has been poured full strength into the cup of his wrath. They will be tormented with burning sulfur in the presence of the holy angels and of the Lamb. 11And the smoke of their torment will rise for ever and ever. There will be no rest day or night for those who worship the beast and its image, or for anyone who receives the mark of its name.” 12This calls for patient endurance on the part of the people of God who keep his commands and remain faithful to Jesus.
It’s very obvious that God has not poured out his wrath yet. The angel is calling out for LAST CALL to repent, worship God and be saved. I do not believe the GT is God’s wrath. These are all PREwarnings, not to worship the AC or take the mark of the beast in the following verses which I have also bolded. It even mentions in verse 9 that God has not in FACT poured out his wrath yet for it says in the following verse
Revelation 14:9-11 NIV
9A third angel followed them and said in a loud voice: “If anyone worships the beast and its image and receives its mark on their forehead or on their hand, 10they, too, will drink the wine of God’s fury, which has been poured full strength into the cup of his wrath. They will be tormented with burning sulfur in the presence of the holy angels and of the Lamb.
I bolded the letter wrath, so you can see that God’s judgement/wrath is not the same as the GT. The Angel gives everyone a fair warning before God pours out his wrath. It’s right there, black and white. That is how I understand it.