Going To Paris 03oct, How Long Will It Take To Get A Passport And What Is The Process?

I plan on flying out of Cincinnati/Northern KY Airport on a direct fight to Paris on 03Oct to see a concert on 05Oct. I then plan on flying home to Cincinnati, from Paris, on 06Oct. When should I begin the passport process to ensure I have it on time (I realize I may have to pay more at this point for quicker service), and what is the process?