Breaking apart a Novel

My starting point, a story concept that I previously came up with, is from one of my random, quick write it down, locations. I have 4 choices that I think would be appropriate. I labeled them each 1-4 and rolled a d4. The roll of 2 means that I will writing the following:

Brother and sister switch bodies, and learn to get along better. A Modern (present day), Humor, Slice of life, Sex story. The main problem facing the protagonist will be: The brother needs to find a way back to his body before his reputation is ruined and continue living the life of the sister, which has several complications such as friends, boyfriends, homework, and using the bathroom. Possible settings of the story would be: High school, downtown, house party, home.

The protagonist would be the brother. The antagonist would possibly be the sister, as she tries to ruin his life, as she imagines he is ruining hers. She could do things like fail tests that he is taking (he would be good at school), get him cornered by her boyfriend, and make him become ostracized for being gay in high school.

The other thing is that I have less than 30 days to write all of this. Which means that I'm aiming to finish in 25 days. That means, 2000 words each day of writing. No ifs, ands or buts. The goal is to reach 50,000 words. Regardless of whether the story has typos or inaccuracies. The only thing I have to do is give it a beginning, a middle and an end by the 50,000+ word mark.

I'll be giving myself 1 day to research and prepare, 1 day to put the project together, and 1 day to relax or as a buffer.

Ciro (short for Cirocco, ancient Egyptian wind) and Cerise (French for cherry) are the brother and sister. The sister has a boyfriend named Jacob (supplanter). The Mom and Dad will mostly be out of it to keep characters down. Ciro will be a loner, while Cerise will have a friend, in this case Jamie (also supplanter) who will want the brother.

Small Basic Hollywood Style Guide:
Opening Scene - The theme of the story
Setting Up the Story
Inciting Incident
Big Decision
Into the Wide Unknown
Getting to Know the Character
Midpoint - At this point the story has reached the midpoint, but that does not mean I'll be at 25,000 words.
Antagonist Returns
Low Point
Ah ha! Moment
Final Push

If I still need more:
Character Reactions to Plot and/or subplots
Relationship Black Moment
Character Revises Life Goals
Possible Re-emergence of conflict or opposition