Poles should be used as soon as the skier has graduated from the beginner's snowplow turn. The slight forward movement that comes as you plant the pole will unweight the tails of your skis and help you start the turn easily. Begin with arm bent and relaxed (not straight and stiff) and plant pole about a foot out from the ski. Then turn around it. When your boot comes even with the pole, push down and to the side with the pole. This pressure assists transfer of weight to the new downhill ski and starts heel push that finishes the turn.
Long turn starts with forward movement of left shoulder and pole while right hand and shoulder move back. This reverse position is held throughout turn. Plant pole halfway to ski tip and in as nearly vertical a position as possible. Use gentle wrist and arm motion or pole will catch in snow and jump back at you. Palm faces forward and slightly upward, then turns toward body as pole goes in. Drawings below show how hand position changes as pole is pulled (left) and then wrist rotates so that as hand is raised it is in proper position to plant pole for the next turn.
Short turn technique is designed to get pole in and out quickly. Shoulders do not move while planting poles but face directly downhill at all times as skis angle from side to side. Skier above is finishing right turn and left arm is raised, ready to position pole for left turn. Right hand has pulled pole from snow and is bringing it forward for next right turn.