Did they even live to hear the noise? Or were they instantly asphyxiated/burned/etc?
I’m sure they heard the rumbles and felt the earthquakes. But the gas and ash was so fast that it caught everybody before they could really do anything about it. This study says it was pretty quick.
A contemporary account of the erruption, by someone who was there.
Bottom line, yes Mt V was smoking for hours before the actual eruption. They knew they were in danger. Many were able to flee, and survived. Others died at the harbour, waiting for a boat that could take them to safety.
Vesuvius almost certainly did some ominous things right before it erupted… But then again, it’d probably been doing ominous things without erupting for years before that. The Pompeiians were probably used to it by then.
Thee evidence is that many bodies in Pompeii were on top of a significant layer of fallen ash before they died in the pyroclastic flow that overran them, that layer was thick enough to assume that it had been falling for a number of days.
So, in answer to your question, they had lots of warning but this may well have been a repeat of a previous event - without the final eruption, and in any case they would not be likely to understand what it might mean, the existence of pyroclastic flows was not known for certain until well into 20th Century, and even now the existence of saltation layers within them which madly accelerates their speed was unknown until very recently so its not like we were any better informed.