I did a pre-order for a Note 7 on Aug 4th. I saw in the forums that others were getting the promotion for the free Galaxy Tab E, so I called tmobile two days ago. A very polite rep looked into it, but said that she couldn't help me without me cancelling my Note 7 order first (which I had no interest in doing). After the call, tmobile sent me a survey, and I answered honestly that their inconsistency with giving some the promotion (even when they ordered on Aug 3rd or Aug 4th, without having to cancel their original order) and not to others was just poor customer service.
Today a manager at tmobile customer service had seen my survey, and wanted to discuss it. After I explained what had happened, she was extremely helpful in getting me onto that promotion. The way she explained it was that tmobile would send me the tablet for free, and that I would see a charge for $10 a month for monthly service, and also a credit from tmobile for $10 a month for 24 months, making the tablet and service "free" (I do have to add an extra line on my account). The only difference to my order from others that I've read about here is that I only get 200mb of free data, while others have said that theirs comes with 2gb. Either way, I'll be on wi-fi or tethered to my mobile hotspot, so it isn't a concern.