Carl Sagan’s Cosmic Calendar (illustrated as a comic strip here), which maps the entire history of our cosmos onto a single year, begins anew with January 1st.  The first second of the first day of the new year corresponds to the Big Bang, 13.7 billion years ago.  Thereafter, the infant universe undergoes a billions of years-long phase of development.  The next major event on the calendar, the formation of our Milky Way galaxy, will not arrive till May.  For an exciting presentation of Big History starting with the Big Bang and continuing to the present day, check out David Christian’s TED Talk.