All ages listed on manga character pages are from before France Story. Ages have to be sourced and not guessed because of the floating timeline. For example, Amon Kunisawa's age is listed as 21, though he has most likely turned 22 or 23 by this time.
Ages of Season 2 characters are current, since only a few months have past in the series.
Birth years are included on several character pages, however these years are considered only partially canon. All the birth years were published before Yoko Kamio established the floating timeline of the series.