I think the only way we get any warning is if we happen to be at a cemetery looking at a saved person's grave, and then it'll only be a split second as the dead rise first and then those still alive. We may or may not register that the trump has sounded. We may or may not register that the dead are rising.
Of course,
@Margery happening to be looking at George's ashes at that moment would get the same split-second warning
Wonder how much noise and maybe air, barometric, earth, etc. disturbance with so many people moving all at once. AND the Holy Ghost leaving
AND satan and his demons moving in lickity split
Wonder if the graves will be opened like when Jesus was crucified, or if the glorified bodies will simply pass through coffins, vaults, dirt, markers, etc. If the former, that'll be some huge noise and earth movement, especially if one is in a cemetery full of Christians!