According to Jewish law, a Kosher menorah needs to contain eight candle-holders.  Eight potentials for light.  If one is lighting on Day 3, it is irrelevant that he does not need the remaining five holders.  They have to be there.
 
The deeper reason:  The ultimate way to maximize growth and potential is to fully act on one moment at a time, while looking ahead to future growth and potential.
 
So that as we celebrate each accomplishment, we can look to the future and know that there is more!