Posted: 20/04/2017 at 22:29
I wouldn't cut into any old wood at the moment ( brown wood ) I will bleed and severely weaken the vine , I would pick a leader now and pinch the other shoot back to 5 to 7 leaves and any sub lateral to one leaf.
It sounds like a Cordon system ? I have pruned my own grape vine into a spur & rod system which is still part of a cordon system, I take some pictures tomorrow if you want. I have a little grape vine handbook which helped me out enormously when I first started growing grapes ( RHS Wisley handbook grapes ) 2008 edition , its about £2.80 on amazon 2nd hand .
A Guyot system may be better for growing grapes against a wall, vine yard grow their grape this way. Unless I've miss read and you are training them is way.