Essentially most characters would only need to know things between 50CE through to the current time.
AeRo is mostly AU after Caligula. However, the births of a few important dates were put in place to assist in working out ages, etc.
OCTAVIUS FLAVIUS ALEXANDER & JULLUS FLAVIUS ALEXANDER
LUCIUS CORNELIUS SULLA MAGNUS & LUCIUS CORNELIUS SCIPIO (I).
QUINTUS FLAVIUS CAESAR ALEXANDER & TIBERIUS FABIUS MAXIMUS