actually, a trainer friend told me na it would take an average of around 30 mins of jogging before you start burning fat; puro carbs lang daw ang nabburn initially.
Sir, we actually burn both carbs and fats at the same time but in different ratios.
More information can be found
here.
There are other sources but this is the most concise one that I found.
Anyway, as for doing cardio, I do moderate-high intensity cardio on the treadmill for a total of 25 minutes after my strength training workouts 3x a week. I do high intensity interval training (HIIT) on my stationary bike at home for a total of 20 minutes 4x a week.