Question about contacting T-mobile to try to get the $930 off the iPhone 18 pro on retired/grandfathered plans

I saw the post a few days ago on here about trying to get this iPhone 18 pro promo on these older plans. I have the One plan and contacted T-mobile through twitter. I told them I was considering switching to AT&T (which I was) because they had a better offer for the iPhone 18 pro. They said they can offer me a one time targeted promo of $930 off 1 device and $600 off a second device. They said I'd have to trade in any device as long as they can get the IMEI number. This sounds great but my concern is that they also said to complete the orders on TLife and once my phone comes in and they receive my trade in, to contact them to have the promotion manually added. I am planning to contact them through Twitter again tomorrow afternoon to verify through another agent, before going through with the order. Has anyone done something similar to this in the past? Did they do exactly follow though like the agent said?