How do I get my forerunner 965 to give me the 5 second count down on intervals? It did it on my fenix 6s pro but I don’t know how to turn it on for the 965

Mine does it for workouts I set up . I don’t recall doing anything specific to enable it 

Same here. I have setup the intervals myself in a workout and then it just does a 3...2...1...GO sort of vibration that tells you when the interval starts and also when it ends. Happens automatically