Good question! Open your Whistle app, and tap the paw icon at the bottom of the app. Your progress towards the incentive milestones can be found in the ACHIEVEMENTS & STATS section, located just under the BREED of your dog. The number of days is recorded in the first row of achievements, on the right-hand side. 

Consult the GIF below for a visual example!

 

WhisteDays_Phone.gif