I signed up two days and and still no credit. I just called and they said "It looks like the voucher and bonus miles will be available in your account on September 16." I'm not sure why there's a week lag time, but that's what they're now saying.
I'm unsure if there's any cooling-off period after canceling DD before you can get the promo again. I've never been part of DD, so I'm not sure if there even is one or if it means you couldn't have ever been a member before.