ANSWER: The answer is no. They are not resurrected at the same time. Paul makes that clear at 1 Thessalonians 4:16-17. In verse 16 Paul plainly states that those dead in union with Christ rise first. The next verse uses the word “afterwards, we the living will…“
So, “first” and “afterwards” indicate the ordering of the first resurrection. The dead rise first, then afterwards, those who are living and who die are resurrected without sleeping in the grave, as those have who will be resurrected first. Together, though, they will all be united over a short period of time, as if in response to the last trumpet.