It’s a bit late, but for someone who knows they can’t get anywhere near that high of a word count so quickly, would you recommend participating in nanowrimo anyway as a way to start getting a draft out for a story idea you’ve been developing for a while?

Oh, absolutely!  Even if you only end up writing 10k words this month, it’s still 10k more than you had before!

I pretty much did this back in 2012 with my sci-fi novel; I’d already done part of it, and did NaNo to finish the rest.  I think I only did about 12k words that month (nowhere near the 50k goal), but I did accomplish a lot with those 12k words!