T-Mobile sends update to Samsung Galaxy S6, Galaxy S6 edge, Galaxy S6 edge+ and Galaxy Note 5
Additionally, bug fixes and stability improvements are part of the update, along with new and enhanced features. The changelist also mentions further improvements to performance. You can try to manually pull it out by going to Settings > About Phone > Checking for updates.
When the update does arrive on your phone, you should make sure that you are connected to a Wi-Fi nertwork before starting the downloading and installation process. Also, you should have your battery charged to at least 50%. And because the update is sent out on a staggered basis, you might not receive it for a few days. Be patient, and you will soon receive the notification that the update has arrived.