That's not the question! It's easy to get both cards and both bonuses if you apply for both "at the same time". It's not possible, in our experience, to get both if you wait until the first bonus posts (but only that long) before aplpying for the second one.

You can either apply for both on the same day, or wait 18 to 20 months between apps. There's nothing in between. Those are the only choices (for the person Citi AA cards).

The reason "both at the same time" works is because it tricks the system into each card app not seeing the other card app. But if you wait, the second card app does see the first card app and says "invalid" because of that.