Well, I can't say I recall you around here before, which I apologize for if you're a regular, but one thing I've noticed is writing often doesn't work that way.
Deciding to do it, then doing it is only part of it, at least in my own experience. My characters often take on a life of their own, so I've learned to just let it flow as they see fit. Problem is, some of my stories end up taking a great deal of time to write. Add to that anything going on in real life that might get in the way, and it takes even longer. But, I find that when I do let the story run its course, instead of forcing it, I'm much more satisfied with the results.
I guess what I'm saying is if you don't finish by the end of the month, don't feel bad about it. Let it flow on it's own, then share it with us, and I think you'll be impressed.