Knowing when to stop isn't so much the problem: it's mastering that heel motion that makes the brake connect with the ground in an effective manner that's the tricky part, so far.

Ah well. At least I have trees and fences to use in the meantime. I'm trying not to be afraid of falling over: after all, I have a helmet and all sorts of protective pads, so in theory even if I do faceplant, the damage should be minimal.