The GREAT BIG PROBLEM is that Hallacha strictly forbids men to create a religious holiday. The Jews are bound to celebrate only the Jewish Feasts. And the Noachides can only celebrate also some Jewish Holidays (without the rites or and ritual rest, for example they MUST NOT do Shabat, but can celebrate the Seventh Day).
Even a date named in Torah for Gentiles, like the end of the Flood or the day the Reainbow appeared in the sky, is forbidden to be celebrated, since Hashem did not order it!!!!! Strictly the only kosher man-made celebrations allowed are secular National Days for patrotism, or one's and one's family birthdays. The rest is forbidden to Jews and Bnei Noah. That's the Hallacha!!!!!!
However I'm not so strict and sometimes remember the beggining of seasons.