The last time I remember that Jim posted percentages for a book’s completion was for Ghost Story. He might have also done so for Cold Days, but I am less certain about that.
In any case, Jim did this on Twitter and in one post he said that the percentage of completion was based on the expected word count Jim had calculated before he started writing. So in a simple example, if Jim calculated; or guesstimated based on past experience, that a particular novel would take 100,000 words to complete, when he reached 90,000 words, he would post that he was 90% completed.
However, there was a problem with Ghost Story. Jim needed an extra ten or fifteen thousand words to wrap up that story in the way that he wanted. So when Jim got to 100%, he wasn’t done. It only took a few more days for Jim to complete, but it was annoying having to wait, no longer having a clue how long it would be. I don’t think Jim ever posted anything that told us how far past 100% of his expected word count he went. I just recall a post that was so short and to the point about Jim sending the manuscript to his publisher that I had to read it twice to be certain.
As of today, Jim has been stuck on 89% for the past two weeks, which does surprise me a bit. I thought he would really be pushing hard to finish before year’s end. Of course, I have no idea what is going on in Jim’s life that could have forced him to put the brakes on. For example, there is a nasty flu going around in North America at the present. In fact, I have heard there are two separate strains of flu currently making the rounds. This might be true as I was vaccinated near the end of November and still got the flue a week later.
Hopefully, whatever slowed Jim down will be resolved and hopefully he has a much better estimate of his percentage of completion than he did with Ghost Story.