John, I’m not sure what is your question.
Have you tried to follow instructions for working with Bluetooth timers in PractiScore app? Bluetooth timers supported in the PractiScore app for Android
Though if you are planning to use Bluetooth timer for a personal practice, you may want to look at the PractiScore Log app. The PractiScore app is crafted for running and scoring matches, but practice is a quite different activity. PractiScore Log app info