Rohatsu means date in Japanese- 8th day of the 12th month. and is celebrated as Buddha's awakening. When we use a date as meaningful it is because of a lingering experience. For example, May 31 has meaning but April 26th no longer does. So, 9/11, December 7th, February 11, 10/10/69 and 9/24/90 have meaning...to some.
Awakening and staying somewhat so, has gavitas. We don't question such the date but are aroused by the experience. This is seeing our true self within the meaning. Meaning is the wrestling of two options weighing options. So as Buddhist we are less interested in date than experience. A date is a printed menu.
Tradition varies as to which date is celebrated as "Enlightenment Day," by Buddhist practitioners. For us at The Falmouth Soto Zen Sangha we don't celebrate the date, 12/8, but undergo the experience. It is the equivalent of celebrating a wedding anniversary by getting married- again. Also this is not a reenactment, just as when we sit it is the same as the original Buddha, for without this being so, the meaning changes, then where is the faith?