#Bash +GNU date, <s>72</s> 70 bytes

    for((;1`date +%d%m -d$d\day`-12612;d++));{ x+=\ Eve;};echo Christmas$x

- one byte saved replacing `!=` with `-`
- another removing extra space

[Try it online][1]



  [1]: https://tio.run/##S0oszvj/Py2/SEPD2jAhJbEkVUFbNUU1V0E3RSUlJiWxMkHX0MjM0Mg6RVtbU9O6WqFC2zZGwbUs1brWOjU5I1/BOaMos7gkN7FYpeL/fwA