Just what the title states -
Does reversal of magnetic poles in a planet refer to the point in time when reversal is complete?
Does it refer to the entire drawn out process (assuming the poles flip gradually from 0 through 180 degrees?
As far as I know the term "reversal of magnetic poles" doesn't have a strict definition, so I suppose different commentators might use it in different ways. However I suspect most of us would use it to describe the whole process.
You describe the process as "drawn out" but no-one knows how long it takes because the dynamics of the Earth's core are poorly understood. On a geological timescale the process looks instantaneous, but then geological timescales are pretty long. Models suggest it could be pretty quick, though how realistic the liquid sodium models are is open to debate.
The wikipedia article wikipedia article on Geomagnetic reversal seems like a pretty good place to start. See the section titled "Duration".
"Most estimates for the duration of a polarity transition are between 1,000 and 10,000 years."... but some people argue (very controversially) that some reversals in the past have been as quick as a few months.