In a capacitive circuit , current leads the voltage , How can it be practically possible as we havn't applied the voltage yet and still current exsists?

In a capacitive circuit, the flow of current is offered by the charged capacitor. The current through a capacitor change instantaneously and the voltage reacts less quickly. Therefore, a large but very short spike in current may lead to a small change in the voltage. Which does not mean that, the current goes first and voltage developed later. This means that, for a capacitor, changes in voltage will always lag behind changes in current.Hence, the current leads the voltage.