As I noted elsewhere, my corp AT&T rep recommended NOT ordering through AT&T, but rather through Apple. He has over 10 years with AT&T in this position and has proven himself unimpeachable in these matters the 3 or so years I've been dealing with him.
His rationale was that Apple hoards inventory and will have more of it to distribute. Also that AT&T was the more popular distributor of iPhones and thus runs out of supply more quickly. He didn't mention any specific delay.
I would trust my guy more than a truckload of random CSRs. My last corp iPhone (which I HAVE to order through the corporate portal) took something like 3 or more weeks to get to me. And I ordered day 1 of preorders.