One thing I do like about T-Mobile is that they really put a lot of energy into taking care of Houston. T-Mobile pulled a bunch of permits from the City of Houston on June 10. Seems like they're not sitting on those permits (which Sprint used to do).
From the few towers I checked, it seems like they are prioritizing towers that were left behind during the 600 Mhz upgrades first. The towers that received the first round of 600 Mhz upgrades have not had any permits submitted.
2.5GHz install on a T-Mobile site in the Houston area: 29.7018566, -95.7397737
Site is only broadcasting two B41 LTE carriers, no N41 as of right now. Talked with the crew for a bit and the four of them are tackling four sites per day right now.