Of course we configure earlier. Configuring for a Flap 3 takes longer, as you know, because the lower final flap drag means an increase in the time taken to reduce to Vapp... hence the earlier configuration. This all happens at idle thrust.
Assuming you start to configure at a point from a Thrust Idle G/S descent (Conf 1) which enables you to become stable at 1000ft as with Flap Full, the timing of that point will make no difference to fuel consumption. What makes the difference is flying the remainder of the approach below 1000ft at 45% N1 instead of 55%.
Just saying...
Last edited by The African Dude; 3rd Jun 2013 at 21:23.