Jeff Butts, MacObserver, sharing info he got from Andrew Woodward, who has his new Apple Watch in hand:

When Mr. Woodward activated his Apple Watch Series 3 LTE and received a text message confirmation, he thought he’d see the green dots on the Watch face. He didn’t, so began the technical support process. After speaking to both his cellular provider and Apple, the thought was that the eSIM was still waiting to be provisioned.

It wasn’t, but Mr. Woodward didn’t realize it until later on in the day. He walked away from his iPhone, beyond Bluetooth and Wi-Fi range. Suddenly the green dots appeared.

Those green dots are the sign that your Apple Watch is flying solo, using its data plan and, likely, using more battery to support the LTE radio.

As you’d expect, the Apple Watch uses the iPhone’s radio whenever possible, saving battery life.

The linked article also walks through the Apple Watch Control Panel interface (swipe up from the bottom of the Apple Watch face), where the “radio tower” icon is white if your Apple Watch is in range of an LTE signal, and green if it’s actually connected and using that connection.

Good stuff.