Defence and counter attack timing

Imagine your opponent is standing, facing you in a right lead stance (southpaw) and he is about to go for a roundhouse kick with the back leg. Firstly he would probably make some kind of movement with his arms (either slightly raise his left arm, or just drop his front arm). Next, maybe a slight pivot with the front foot, or moving it slightly forward, then his knees would bend as he lifts his back leg of the ground, whilst still moving his arms in a direction natural to him to generate momentum. Finally his kicking surface, (shin, instep) would be swung into his choice of target (probably thigh, midsection or face). Now all of this would happen in about 1 second and most beginners would start there defence or counter attack when they see the leg swinging in towards them. The best timing to start your defence or counter is WHEN YOU SEE THE INITIAL MOVEMENT. In this case it would be as soon as you see his hands move, or if not then, then no later when his front foot moves. This is the work of the advanced fighter, and if you decide to counter (maybe a stop hit jab to the face which is quick) you most likely should always hit with it, as the last thing on most opponents minds when attacking is to be aware of there defence. To create this kind of quick reacting takes a lot of practice through sparring and a lot of understanding of your opponents initial movements before attacking, but it can be your most greatest ability when fighting!