It may seem like a dumb question at first, but we’ve categorized past centuries into time periods, like the renaissance, the age of exploration, etc., so how would we know when a “new period” begins?
This definitely is not a dumb question, and debates like this are present in many different fields.
These periods are typically "created" long after they have happened. People typically do not realize they are participating in larger historical movements, and it takes a long time for people to be able to break down and discover causes and effects and trends.
Peter Brown's book, The World of Late Antiquity, describes a period of transition between the fall of the Western Roman Empire and the early Medieval period. This was written in 1971, more than a thousand years after the events that took place and is usually seen as a work that brought the idea of Late Antiquity to modern historians. In years past, this era was known as the Dark Ages, a time of inward regression and intellectual collapse, when recent historiography shows this was not the case.
To state it simply, we don't know when a new period is occurring. We won't know till a decent amount of time has passed, the dust has settled, and the evidence can be examined in a neutral manner.