Countdowns also make me nervous, but the idea is to "hurry so you focus on the essentials", personally I limit myself lately to 5 min gestures, as it still gives that feeling of "focus on the essentials" while still being a generous amount of time to take things "calmly".
Try different amounts of times and see which work for you.
I don't remember if this site was suggested during the course or how I came to find it, but it's useful for gesture practice https://quickposes.com/en/gestures/timed