It sounds like synesthesia. Some people see the year as ring-shaped in their head. The "visualization" is consistent during the lifetime and can help memorizing dates.
I don't have this, though I do have a consistent "visualization" of numbers under one hundred (and, yes, months, and days of months, and weeks) since very young. Probably helps a bit to memorize some stuff, though I can't compare with the same me deprived of this view. I'm not great at remembering birthdays but not terrible either.
People with such visualizations don't even always realize not all people see them the same way, or at all for that matter.