It's only logical that there actually must have been one very first Age, immediately after the Creator made the Wheel. Of course, after countless turnings of the Wheel, the names "first Age", "second Age" and so on lost their meaning a bit, since you could also call them the 1081. Age and the 1082. Age (or whatever would fit, if you count all Ages that ever occurred). However, since the particular Ages basically always have the same activity, it makes sense to name them always from 1st Age to 7th Age and not continuously increase the numbers in the names of the Ages or change the particular numbers of the Ages (at least from the PoV from an omniscient narrator).