T-Mobile has begun pushing the Android 6.0.1 update to both the Galaxy S6 and Galaxy S6 edge. The update, which weighs in around 1.2GB, bumps the Galaxy S6 to version G920TUVU3EPD1, and the Galaxy S6 edge to G925TUVU3EPD1. T-Mobile has not posted a full changelog, and instead it just reads "Android 6.0 Marshmallow" with N/A under the improvements category.
You should receive a notification for the update, but if you don't want to wait you can check manually. To do so, head into Settings, then About phone and finally check for the update. Be sure to let us know how the update works out for you.