i think it is better to wait at least 6 more month ( you will have to use amex at 1-9% utilization and PIF each month. Your FICO will jump, I estimate ( though it's hard )around middle to upper 700's.......and that is the time to apply for discover to get prime rate and terms.
Some people who have applied with your scores, got their subprime card that is underwritten by discover partners. I would avoid this card at any cost. It has annual fee, high APR and such.
Right now you are on your way to the PRIME life. Apply only for cards from BOFA, WAMU, CITI, WELLS FARGO, Merril Lynch, Schwab, AMEX and DISCOVER. in 6 month that is. if you apply once in 6 month you'll be in all set.
Also, try not apply for any type of "consumer finance" loans that are run by major prime lenders, they are: Citifinancial, WellFargoFinancial and alike. They will all hurt your FICO and hurt your chances of owning a prime card such as discover.
Good luck.