You should see a heavy crema in your Aeropress. This is a cup I just made today from yesterday's roast.  Roasted coffee begins to break down and lose flavor and potency after two weeks. If you are buying from a local roaster, I challenge you to find out the roast dates on the coffee you are buying. I've regularly seen dates of two to three months old on unopened bagged coffee. And that stuff in the grocery stores...forget it.