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.
GAIUS JULIUS MENTO POSTUMUS & TITUS STATILIUS TAURUS.
LUCIUS PAPIRIUS NATTA & GAIUS VITELLIUS SCAURUS MAJOR.
OCTAVIUS FLAVIUS ALEXANDER & GAIUS SESTIUS VATICANUS
LUCIUS AQUILLIUS FLORUS & MANIUS RUTILIUS CYPRIANUS