If you are not going to be able to finish your fic that's fine, I just want to know. You can either reply to the email or PM you got with your assignment, or leave a comment in the mod contact post. There are no penalties for dropping out, as long as you do it before I start chasing you for your story. If I do have to chase you and you then drop out, I might well hold a grudge for future rounds.
Posting is between 27th and 30th October. That means that if it's the 27th, 28th, 29th or 30th October in any time zone, you can post. You can either post to this LJ or to this year's collection on AO3 or both. You can post it in other places too, as long as you do at least one of the above.
When you post here, you can either post the whole story or link to it somewhere else. Bear in mind that you have to be a member of the comm to post and I have to approve all members, so don't leave your membership request to the last minute.
On 31st October I'll post a masterlist of all stories and chase anyone who hasn't posted their story. You'll get one day to post your story; after that it'll be too late.
All other information can be found in the FAQ.