Not sure when to move it, but to get it up to your 2nd floor porch you are going to need to give it something to climb, it should make it up relatively quickly, grapes do grow fast.

I wouldn't move it now while it's growing. You don't want to disturb the growing flow. Let it go dormant, then transplant before it wakes up in spring. After you move it, you can prune it to your desired shape. Train the strongest healthiest arm for your trunk up the way you like. Don't remove the other growth, as it helps establish a good root system. Just train how many arms you like the way you like and then you can remove the unwanted growth before spring starts.

i want to know when is the best time to move a grape vine in south carolina