When does the Coriolis effect become an important factor while sniping?

The Coriolis effect is more esoteric, however, in theory, something easy to adjust for, as it is a function of distance from the equator. A sniper can make a few test shots upon getting to a new location.

They can tweak his or her sights accordingly. It is done to correct any maladjustments from jostling in transit. However, it can be done to compensate for the Coriolis effect too.