One of the great things about Solo: Swipes is that you can set your phone to vibrate when the time has been successfully sent to your Turner Watch. To turn Vibrate Mode on, enter the NKTW App and head to the Dashboard by selecting the gear icon in the bottom left-hand corner of your screen. Toggle on the switch labeled "Vibrate Mode" (it should be green when it is turned on).
If you have an iPhone, you'll also need to make sure you have your phone set to vibrate on either ring or silent. To do this, go to your phone's Settings app. Then, select Sounds & Haptics and turn on either Vibrate on Ring or Vibrate on Silent depending on what your phone is set to.