Pliny's account, from nearly 2,000 years ago, is the first recorded description of a volcanic eruption!
It contains vivid details that certainly give the impression that people in Pompeii had time to react to phases of the eruption.
But, at the same time, Pliny was not in Pompeii himself—he was in a town called Misenum, not far away, but far enough that he was having a different experience.
The argument might then change to whether or not people in Pompeii would have had a similar experience.