I was the only person at my early interviews who wasn't a superstar from a school like the Ivies, U Mich, U Chicago, MIT, etc. last year. If anything it might actually mean you have to up your game and perform better to have a good chance vs. someone who interviews later in the year, but that's just my personal experience.
An August interview is great, but there are no guarantees. Schools tend to be a little less critical during the earliest part of interview season, because they have X amount (usually 150+) of seats to fill. They NEED to do their best to fill their seats. But they don't want to fill them with garbage.
Think of it this way: you run a business and you need to hire a TON of workers, otherwise your business is going to have trouble. Does that make you willing to hire slightly less stellar applicants at first? Sure. Does it mean you'll take the guy with the neck tats, piercings and a couple felonies to work in customer service? Not if you know what's good for your business. But as you get to a point where you only need to hire a FEW workers, you can be a little more particular in who you choose.