Oh, thank you so much!
It depends.
With 5 minute sketches, I usually start with gesture and refine it a bit.
When it's a longer session, I tend to start with the torso, find the middle line going through the upper body landmarks and construct the body from there, trying to find the other forms loosely by eye, by measuring and empty spaces.
But I'm not really sure if maybe it would be better for me to start with gesture even in longer sessions, still finding out :)