Does Advent mean waiting for Jesus who already came two thousand years ago? Liturgically, Advent is about the Incarnation still unfolding its light against darkness, still making its way into our awareness.  St. Anthony of Padua explains Advent this way:

There are four Advents or comings of Jesus Christ.  First, his coming on earth as man; second, his coming into the soul as sanctifier; third, his coming at our death; fourth, his coming in majesty on the last day. Therefore Advent is the celebration of these comings.