I measure my first draft progess with a daily word count. I keep an Excel spreadsheet and happily (or not so happily depending on the output) add in the daily total.
Like a lot of authors I tend to overwrite initially, putting in all that excess description, adverbs and adjectives, and so subsequent drafts tend to have a downward trend in the word count. Although I know this, it doesn’t help in the motivation stakes, and makes it hard finding a measure of progress when your word count is less than the previous day.
Last year in the 2nd semester of the Advanced Writing Course I did, we had different writers join us each week as guest tutors. I asked several of them about their thoughts on word count and progress, and if they had some magic recipe for another measure. Most agreed word count was good for a first draft, but after that it was more important to polish and improve the writing/plot/dialogue etc and not get so hung up on the word count.
Hence my reason for setting a goal of hours and days each week for my work in progress, and to have it ready to send out by the beginning of March. For so far it’s going well. A work deadline sidelined me for a few days, and some days have been less than my target, but others have been more.