I don't like the BBY/ABY dating system in Star Wars, it feels like was created for fans in reference to the first movie, it's not exactly based on anything in lore like how events in LotR are dated.
Like how about for an epoch we use the founding of the Old Republic 25,000 years ago, or the Battle Ruusan which acts as an entire reboot of the Old Republic, or the
Great Resynchronization which was essentially the equivalent of the implementation of the Gregorian Calendar, the founding of the Galactic Empire, or the Battle of Endor which marked the final defeat of the Galactic Empire?