viime aikoina is understood to refer to a continuous or repeated action. For example, one cannot say Poikani kävi täällä viime aikoina ("My son was here lately"), if he visited just once. Words understood to refer to a one-time or well-specified event include: hiljattain, äskettäin, taannoin.
Etymology
viime(“latest, last”) + aikoina(“essive plural of time”)