LoCoWriMo
LoCoWriMo or Local Conlang Writing Month is inspired by NaNoWriMo, National Novel Writing Month. It started with a post by Arthaey Angosii to the CONLANG mailing list (11 June 2009), proposing that several of us simultaneously write a sizable piece of original fiction in our conlang.
NaNoWriMo sets a goal of writing a novel-length story, 50,000 words or more, in any language (but usually, I suppose, one's native language), between November 1 and November 30. Few if any of us have sufficient fluency in our conlangs, or conlangs thoroughly developed enough, to make that a realistic goal. Arthaey suggested 5,000 words as a goal for writing in a conlang; after further discussion we decided each person participating would set a challenging but attainable goal for themselves based on how complete their conlang is and actual experience with how long it takes to write a certain number of words (or characters, lines, pages -- however you want to measure your progress and define your goal).
Since some of us want to participate in NaNoWriMo in November, we're probably going to do this in October.
As with NaNoWriMo, one should start a new story from scratch on the first of October. Writing a plot outline or character background notes, figuring out what words you're liable to need and creating vocabulary for the semantic domains involved in the story you'll be writing, figuring out pragmatics and stylistics issues you haven't addressed before (e.g., how do dialogue tags and reported speech work in your conlang?) -- you can and should do that kind of thing ahead of time; but the story you write for LoCoWriMo should be written entirely during October, not incorporating previously written scenes.
To figure out what would be a challenging but attainable goal for you re: writing fiction in your conlang, it makes sense to do a timing exercise ahead of time; write a different story, or just some stand-alone scenes (for this purpose you don't necessarily have to have a plot sufficient for a complete story), time yourself, and measure your output for a writing session. Given your words (or characters, lines, etc.) per hour for this practice run, estimate how much you could write in October if you give the project most or all of your free time for the month.
Alternatively, you could just start writing on October 1, time yourself and measure your progress for the first writing session, and then set your goal for the month from there.
Why LoCoWriMo?
National Novel Writing Month started out as a U.S. project and has spread internationally since then, but kept the name because the abbreviation sounds cooler. This project looks to be international from the start. Someone suggested Global Conlang Writing Month, but LoCoWriMo sounds cooler than GloCoWriMo. (See the CONLANG thread linked below for details.)
Preparation
While excessive planning of your story is discouraged, excessive prep work of your language is encouraged. If you know you're going to write a fantasy story with dragons, elves, and sword-fights make sure you've got those words ready. Similarly, if you're writing about an office-worker make sure you know how to talk about spreadsheets. The fewer words and constructs you have to come up with the more time you'll have to actually write your story.
Many Wrimos have only the vaguest of ideas of what they will write about on November first, and those who do plan ahead are encouraged to not do much more than a simple outline and listing of characters. The goal is to have fun being creative not to write the next masterpiece.
Rules
In general we're following the same rules as NaNoWriMo. Whatever you write must be new (no continuing an existing story), and fictional. The goal you set for yourself should be difficult, but attainable. Lack of sleep, and excessive coffee drinking is common among "WriMos".
Like NaNoWriMo, the emphasis here is on quantity, not quality. While you should, obviously, try and make your story grammatically correct editing to improve plot, continuity, or anything else is discouraged. Just keep writing. With NaNoWriMo the goal is to complete a novel (technically a novella) within in month. While we may not be able to accomplish the same thing with our conlangs, we can do our best, and along the way many of our languages will improve greatly, which ties in to the lack of editing. By the end of the effort many of us will find our words and grammar have changed in non-trivial ways. If we were constantly going back to update the start of the story to match the the language at the end we'd never get much written.
