I have researched how to train and I have found this far that I should cut back to one main vine. The vine I purchased has three/ four vines that have new growth at each segment all the way up each of them. These are laterals correct? Now before I prune I want to make sure I have this right.

I should choose one older growth vine among the four and prune back the others

I should then choose one or two? laterals(new growth) to grow to the trellis.