Electricity is moving electrons (or other charged particles such as ions or atomic nuclei). Electricity is a form of energy. Anything that conducts electricity has electrons available to move all of the way through it. If you apply a voltage (potential difference in charge between two points in an electrical field), electrons will immediately move through the conducting material where you applied that voltage. There isn't a "starting point", because in order for electrons to move, they have to have a closed circuit to circulate; electrons just start moving when the voltage is applied, but there is neither a starting nor an ending point.