i agree with ayase. it shouldn't take you too long to do.
if you brainstorm characters, plot and places then start on framework on it, then it'll make the writting alot easier, if you started yesterday then by today you should be through the first 150 - 200 words with ease.
Like with most writting, the best work is done on prep and framework. i remember in my english Coursework i had to write a brief story which lasted for as many pages as we want and no less than a single page. i submitted a page and a half of writing and got an A*. mainly because i'd done the framework beforehand. the rest was description.
remember that quality over quantity will aid you much more than drabbling on for 20 pages.
Play on your strengths and try your best at your weaknesses (for me descritpion and imagination are my strengths)
be sure to send us a draft or something