We're expecting our demo to have 3 chapters and estimating the wordcount to be 36,000 to 41,000 words.
Currently we're almost done the first chapter and have slightly over 10,000 words of script at the moment. I would say the current draft of our demo script is about 1/4th complete. While that doesn't sound like much, a lot of work has been done redoing our script, and our outline document itself is over 32,000 words, which obviously took me a considerable amount of time as well.
There's a lot of ways you could collab with writers on PSL for this project to get this chugging along nicely, I think. You might present the script so far - 10,000 words takes like half an hour to read at a leisurely pace - and have writers pitch their ideas in-thread. From there you then take it to further fleshing out, either with a closed group of a few writers, or through an open discussion.
