This could be a formal thing or something as simple as you going, "By Jove! I think I will write a happy ending fic!"
(And yes, I still love angst but sometimes we need some happiness too, yes?)
So, a Happy Endings kind of fic thing should be:
A proper ficathon with a list of prompts and everything!
It could be a fic table!
It could be a one-day prompt at Lostsquee
Just a simple "Write a Lost Happy Ending Fic" will suffice
And the timing should be:
Right after the season finale
After we've had time to process the season finale
Something ongoing, with no particular deadline
Doesn't matter, I won't have time/am not interested anyway!