Good afternoon, Aidan. [pleasantries always come first with Lacus!]
I tend to approximate dates based on the weather. Although occasionally Acumen will announce celebration of a holiday from my culture, and that is also helpful. Important days like that should be remembered, after all.
I tend to have the moon shift phases in similarly timed phases. [If you've noticed the stars and moon that appear on the dome after lights out? She controls that.]