the tendrils wont do any real damage...but if you take them off of the trunk it won't hurt
there is plenty of growing season to go for you.. there is more than one school of thought on guiding a vine to fruition (pun intended)
i cannot say i understand your climate and growing season, so i will only state what i do....
let the vine grow and forget the idea that it 'has' to look like a trellised vine this year and next year prune back to your best buds on the trunk which should be at least pencil thickness ( a vine that had a lot of photosynthesis will have a trunk or more than one that fits this description. I saw a picture of a fellow in NY that had tried to make his vine look like a trellis picture perfect vine in his first year and the picture of his second year (spring) was one of a spindly weak looking thing that should have been cut back to about 16 inches from the ground.
Trust me...I *understand* the desire to have a vineyard look like a vineyard whether its 1 vine of a hundred vines....all the effort you put in tugs at you...you want to see results and it is usually preconceived notions held by you or others witnessing what you are doing that guides this desire.....close your eyes to those thoughts.....the vine has no ideas like this.....and its needs do not fit these notions.....it needs a benevolent parent that knows that its root system is what it needs to develop that first year, just like a newborn has to have its proper milk before anything else
in the first year, do what you have to do to keep the leaves off the ground and use the year to get to get yourself in a pattern and schedule of what needs to be done on a routine basis...fertilize regularly...get the beginnings of a spray program going...and do what weed control youhave to get going.
I remember going into my second season a lady walked by the vineyard after i had finished pruning and she said she felt bad because she thought i had lost everything over the winter.....it hit me at that moment that indeed it did look that way...after all i had just removed 95+ percent of the wood from last years growth...and i admit it was hard to cut back trunnks and cordon quality canes....but that second year you are going to get explosive growth that you *can* train into beautifully shaped trunks and cordons...not that mine are beautifully shaped hahahaha, i had to endure a learning curve...but i can tell you this...because of my first go 'round w training my second group of vines planted last year WILL be beautiflly trained this year as i was more severe in the pruning of the last four hundred vines added than i was w the first 1000+ in fact a friend who helped me prune this year so he can correct his own vineyard said over and over again how severe i was compared to what he thought should be done....he would find himself constantly trying to leave a lot of wood on what he was pruning because he has the *save* and *protect* and care mentality when it comes to plants in general and time and time again i would walk by what he pruned and cut 50% off the vine as he had left it
Because of our cold climate i was more fearful about what would make it thru the winter, so you would not find it uncommon to see 2-4 trunks on a vine in that first group and straight was not always possible....and i will whittle those away w time to just one or two trunks...this last group is 90 percent one trunk....maybe sixteen inches from the ground and i know they will be explosive in their second year...and at next years pruning ( their thrid leaf) they will look like a properly trellis vine and in their case it will be VSP
i want to add one thing that i think is VERY important and i have witnessed this myself.....i have seen wood left on a young vine because someone wanted to save that nice straight wine vine wood that was trained the year before....and then the second year growth was so vigorous that it superceded the size/diameter of the wood from that first year....so you had a baseball bat being supported by a toothpick...the trunk at about 10-12 inches was nice and then it tapered to something thinner, but the person thought it *looked* like a vine so they kept the fruit of their previous years labor....forget that idea....cut it back in the second year to between a foot and maybe 18 inches off the ground....you wont be sorry
anyways..i ramble
what trellis system have you decided or thought about for the long term?