I'd do it on a weekday, skipping class for one last time because fuck my professors.
In the morning, I'd cover all the windows in the house so no light can reach. Hide away in my room for the first part of the day, getting drunk on vodka and coca cola, ignoring the fact that I can't drink because of meds. I'd spend the day writing my note, explaining how everyone has wronged me and how much I wish they'd choke. I'm spiteful and I don't care. I don't want to be seen as a victim. Then, I'd cut my hair short, style it how I've always wanted to but was too afraid to try. I'd then dress myself in the nicest of my clothes, put a shit ton of makeup so I look my absolute best. Then I'll leave a note for my mother, 'im in the basement'. Knowing her she won't even check once she comes home, so I'm not too worried about her interrupting me.
I'd feed my kitty one last time and give him the biggest kiss on his cute little head.
Once it's around 6pm, I'd go down to the basement, lock myself there so no one can come in unless they REALLY try, and hang myself. I'll probably be found the next morning, and I'm hoping my makeup will still be in place. My note will be in my pocket.