It’s the summer before my senior year of high school! I’m planning on applying to 5-8 colleges in the fall. Should I start writing my college essays right now since I’m basically free for the summer (other than some summerwork)? And would you recommend that I write one essay per school? I’m aware of the Common App but I think all the schools I want to apply to require an extra essay.
YES … A thousand times. Start now!
Now. 
Agreed. Now. The summer before senior year is the best time to write those essays. By the time the fall rolls around, you will be so busy and you do not want to ruin Thanksgiving and Christmas by trying to make deadlines under pressure.