Hmm. This video kind of debunks the theory that people were going about an ordinary day when they died? It looks like they had plenty of warning with the quakes and then the effluence from Vesuvius.
I always thought the devastation was pretty much instantaneous.
There is a great book if fiction about Pompeii that I always recommend to anyone interested in Pompeii. It is written from the point of view of the city official in charge of the water aqueduct—which goes out of order due to quakes prior to the eruption. It is so very interesting about the Roman aqueducts construction and engineering and everyday life while a conflagration is brewing in Vesuvius.
Pompeii, by Robert Harris is very off-price reasonable on line now at several locations.