We switched to T-Mobile on Saturday. I wanted the Rose Gold 6s 128GB (my wife) and the Space Gray 6s+ (me). Both had to be ordered because they were not in store. Which I understood, both because the Rose Gold is popular and I was asking for 128GB models.
Despite a false start (the rep put in for a Space Gray 128GB 6+, not the 6s+) I had BOTH phones by Tuesday.
The rep handling my ports yesterday was still waiting for her RG 6s - which she had preordered!
The T-Mobile I went to in Lexington, KY had space gray, silver, and yellow gold 6S's in stock. Walked out with a 16gb gold 6S for my wife. They did not have 6S Plus's in stock that day or when I checked the next week. Mine had to be delivered.