First low brace! The sooner you are there the better. I generally narrow the last 6" to 8" of each limb, sometimes early on, sometimes after first low brace. By waiting until first brace you can see how the string, under tension, will track along the bow. By waiting until then you can adjust that string tracking by removing wood from one side or the other of the tips...and I do the handle area the same but mostly not until first brace.