Prince of Spires
Istar
Since I like arguing with people, I'm going to (slightly) disagree with you here. Not on 536 AD by the way. Wonderful time to be alive really...On the subject of transition periods being somehow gradual... that's not how real life works. So, homework. Search 536 AD.
But I am going to disagree about Ages and being gradual. Some are sudden. Something happens. Some guy in a boat discoveres a new continent or someone decides to cool the planet by 2.3 degrees in a matter of days.
However, just as many Ages shift gradually. Our current Age, if you could call it that, is the Age of the Internet. It started, depending on who you ask, either on April 30, 1993 when the WWW went public or on August 24th ,1995 with the release of Windows 95. You can't really get more specific than that really. We have the exact date.
Except that, having lived through that period, I know that it doesn't work that way. Arguably, we're still transitioning to the internet. Nothing changed on August 24th 1995, except that Bill Gates became a lot richer. Other than that, no major cultural shifts happened. People didn't shop any different or behave any different. Amazon wouldn't launch for years, and it started as an obscure book shop. Same with Google or Wikipedia or Facebook. Companies like Uber wouldn't come into existence until after the rise of the smartphone brough a second age of the internet. Most people didn't have computers capable of using said internet.
Other than a news item, most people didn't notice the age of the internet had begun. And no one realized exactly how big the impact would be.
Same with plenty of the other ages. Yes, the middle ages started on September 4, 476 AD with the fall of the western roman empire. Again, a specific day. However, very little actually changed for people in Europe on that day (unless you were Romulus Augustulus of course). Someone in Brittain or Spain or North Africa wouldn't have noticed anything. The collapse of the Roman Empire was a gradual thing, which affected different places at different times. Rome had long since stopped controlling anything other than a small bit of Italy, and the fall only really formalized something that everyone already knew.