Sure. Disney World. If I take my family on vacation the balance is usually due 90 days before our stay with a $200 deposit. Or a preorder at Gamestop.
You want the device and you're going to pay the same sum regardless. You're buying the device and locking yourself into being one of the first to have it. It seems to make sense.
Paying for a service versus a tangible item like a phone are not the same. A reservation at Disney World (or restaurant, hotel, movie theater) is for a piece of time that cannot be replaced if you cancel last minute. If I cancelled my order today, TMO can still sell the phone to someone else.
As a separate comment pertaining to being charged days in advance for an item listed as shipped that wasn't shipped and using the excuse that TMO has to process all these orders, so they must do it days in advance, I say bologna! Amazon ships an average of more than 3.3 MILLION packages a day, yet has no problem with not charging your credit card until a few HOURS before your item is boxed up and actually shipped! TMO said these phones would be shipped OVERNIGHT, so if they marked them as shipped and a customer did not receive them the next business day, which is OVERNIGHT, then any of us have a good right to complain!.
A bit off topic, but very similar. I often buy some phones on the site Swappa. Their policy is every device purchased must be shipped within 2 business days. I had one seller send me the tracking number for a shipment, which was just the USPS Priority Mail label, but did not actually tender it to the post office for nearly 10 days after. I disputed this charge with my Chase card and was refunded the purchase price. Not that I wish to do the same with the Note 7 I ordered, assuming it will arrive this week, but I could dispute this charge as well and win on the basis that TMO stated overnight shipping and did not deliver the item within one business day of it being listed as shipped, which the email sent to me and the UPS tracking information easily prove they did not fulfill their commitment.