T-Mobile has now also sent out their update OTA. Priv owners should find it readily available when checking for updates.
The unlocked BlackBerry Priv has already received its monthly security patch for March, and now AT&T is pushing its update. We've seen the carrier variants get the updates anywhere from 3 days to 3 weeks after the unlocked version, and this one is on the later end. The update originally pushed out on March 7, which is two weeks ago. With this, you'll have the latest Android security patches from Google on your Priv.
If you haven't received an update notification, you can check for the update manually. To do that, head to Settings, then About device and finally check for update.