Irenaeus (around 200 AD) wrote about the Church being ‘suddenly caught up’ and then “tribulation such as has not been since the beginning, neither shall be” following that. This is in his Against Heresies.
Irenaeus also wrote of the three core tenants of dispensationalism.
Ephraim the Syrian and Eusebius (approx. 330 to 370 AD) also wrote about a pretribulation rapture.
You need to provide the text of these, since without seeing the exact quote in context is useless.
Christians from the beginning believed that those that are living at the time of the Second Coming will be taken up to heaven at that time (1 Thess 4:17), but until the 1820's, NO Christian believed in the novel and cobbled-together End Times schema of modern rapture-at-any-moment Dispensationalism.