Within a week or so after planting, use clean shears to prune the vine back to one stem. Choose the healthiest, strongest stem for best results. You must also cut this stem back to two or three buds. As new growth begins to develop, determine which shoot is the most vigorous and remove the others. Use paper-covered wire ties or twine to loosely attach the growing vine to your training system.  Since the vine is still small, it may not be tall enough to reach the wire of your trellis system. For this reason, consider installing a bamboo training stake directly beside the plant. Tie the fresh vine onto this stake, then remove the stake once the vine is tall enough to reach the trellis wires. You may need to tie the vine on a weekly basis. Continue to remove any side shoots that develop during this time. Once the vine is tall enough to reach the wire of your trellis system, cut the growing tip back to the top bud.  Doing this forces lateral buds to form. Lateral buds will form cordons that need to be trained down along the wires of your trellis system. Tie them onto the wire loosely. After the cordons reach their full length, you can let side shoots develop. These side shoots will need to be cut back to two or three buds each dormant season, though. These buds will develop into shoots that produce both flowers and fruit.

Summary:
Prune to one stem after planting. Remove weak growth. Loosely tie the growing vine. Cut the growing tip once the vine is tall enough. Maintenance prune during the dormant season.