We planted last December a row of Ligustrum Lucida shrubs for tall privacy (as you can see, we are in open view of our neighbors). In a year it grew in a very spike-like, sporadic manner (see pics). We have not trimmed it yet. This type of Ligustrum produces a LOT (!) of black berries. We don’t need the flowers or berries (the hedge is behind the pool’s short wall). My question is:

• How & when should we prune
  the hedge to encourage VERTICAL growth (in height)?
  TIA for all your input.