So get this - I have a line that shouldn't have been ready for an upgrade until October, but showed as payment plan available. Whatever, I went through the screens, and I was trying to get the $100 for trading in a smartphone. Wouldn't come up at all with that bonus. Called, and the rep said "Well, since you're not really eligible for the upgrade, it's just a targeted special promotion for you as a loyal customer, so you're not gonna get that too." I said "The text just says "trade in a smartphone, working, and do it as an upgrade. Nothing about time or other constraints."
So be careful, they may try to bone you on that. I'm trading in an old Razr M - completely not worth a hundred bucks on Ebay, but there you go. I plan to get the S7 in hand, call them and ask about the 100, and then make enough noise that they give it to me as an account credit to make me go away.