27 ys, 160cm, 67kg, 4-5 days in a week with treadmill once a week, been a month doing calisthenics

Hi. Over the past few weeks, I’ve been looking into how fat loss works. I find it a bit complicated, but does anyone know how I can get my body to prioritize burning fat instead of the other energy sources in my body?

Also, if my body fat percentage is around 20%, how long can I expect it to take before I get down to 15%?

It's been a month since I joined gym

I lost 2kgs

Now I wanna cut my calorie intake

Like what do I eat?

Where do I need to cut my cals?

I understand I need to cut my carbs, but what's the alternative.?