Here are some scriptures about the resurection to heaven and rapture and the time point:
51 Look! I tell YOU a sacred secret: We shall not all fall asleep [in death], but we shall all be changed, 52 in a moment, in the twinkling of an eye, during the last trumpet. For the trumpet will sound, and the dead will be raised up incorruptible, and we shall be changed. 1 Corinthians 15:51,52
15 For this is what we tell YOU by Jehovah’s word, that we the living who survive to the presence of the Lord shall in no way precede those who have fallen asleep [in death]; 16 because the Lord himself will descend from heaven with a commanding call, with an archangel’s voice and with God’s trumpet, and those who are dead in union with Christ will rise first. 17 Afterward we the living who are surviving will, together with them, be caught away in clouds to meet the Lord in the air; and thus we shall always be with [the] Lord. 1 Thessalonians 4:15-17
8 And another, a second angel, followed, saying: “She has fallen! Babylon the Great has fallen, she who made all the nations drink of the wine of the anger of her fornication!” (.....) 13 And I heard a voice out of heaven say: “Write: Happy are the dead who die in union with [the] Lord from this time onward. Yes, says the spirit, let them rest from their labors, for the things they did go right with them.” Revelation 14:8,13
So the resurection to heaven according to the Bible begins after the destruction of Babylon. Then a 1260 days, also mentioned as 42 months and 3 and half years will elapse during which the choosen ones if they die or are killed get resurected immediately.
But then the rest of the choosen ones will not die but they will be changed from being humans to be spirits. Jesus tells when it will happen in following scriptures:
30 And then the sign of the Son of man will appear in heaven, and then all the tribes of the earth will beat themselves in lamentation, and they will see the Son of man coming on the clouds of heaven with power and great glory. 31 And he will send forth his angels with a great trumpet sound, and they will gather his chosen ones together from the four winds, from one extremity of the heavens to their other extremity. -Matthew 24:30,31