STEPS:

Open the NOWATCH app.
Tap 'Login' to connect an existing account or tap 'Create an account'.
Tell us about yourself by filling in the required information. This helps the algorithm learn.
* Date of birth
* Height
* Weight
* Gender
* NOWATCH wrist
* Dominant hand
Tap 'Save'.
Make sure your device is not in shipping mode. You can take your NOWATCH out of shipping mode by long-pressing the crown for 12 seconds.
Your NOWATCH should vibrate. If it does not, make sure your NOWATCH is charged.
On your Android device, turn Location on. See here how.
On the Pairing screen, click 'Next' (picture 1).
Click the 'Pair” button (picture 2).
Your phone will start searching for your device (picture 3), and a pop-up with one or multiple “NOWATCH X NX numbers will appear.
Choose the NOWATCH X NX number that matches the number on the back of your device.

Now you’re ready to go!

HOW DOES NOWATCH CONNECT TO MY PHONE?