I'm getting ready to prune down some grapes on a trellis here at the home ibought a few years ago. they have never been pruned by me, and the old timer here before us died leaving the house vacant - 7+ years of pure wild growth.
Where abouts are you located? Last year in my part of Indiana it got down to -17F and that wiped out many of the smaller vines sections. I was nice in that I didn't have to prune . If you're also in an iffy area, then you might want to wait until the buds start to swell so that you know the vines you are leaving are alive.