If you're 20 years old and you've had a credit history since 18 years old, I think you can get approved for Sapphire Preferred. I just got a confirmation for CSP approval emailed to me. I'm 19, have student loans, and my credit scores are almost similar to yours. 

GOAL: Buying a home before age 25 and maybe an Amex Black Card or JP Morgan Pallidium x.x before my life is over lol...*cough*