r/grapevines

I recently purchased this Niagara grape vine but I’m not sure how much to prune to improve its first year growth. Should it only have one main stalk?

Over 10 lbs of sweet juicy grapes. They were growing on the side of the house I inherited from my mom from a vine she planted years ago. Going to make some wine.

My neighbors had to move recently (late May), and they offered us their six year old concord grape vine and twelve year old champagne grape vine. We live in Reno, NV. I pruned them back, about six feet off each side, to what's shown in the picture. For the concord, I was able to get a little over a half foot of root ball and for the champagne around a foot-sized root ball (I was limited by how much I could take due to decking they had near the vines). I transplanted them to these planter bags with soil and compost. I plan to put them in the ground eventually; I just need to figure out where in my yard would be best for them. My question is whether should I continue to prune these new growth shoots to promote root establishment, or is it okay to continue to let them grow as they are? Any other tips and recommendations are certainly welcome.

(reposting because the image didn't previously attach)