Hello, check out my previous post related to grape vine.
Now would be a great time! It appears to have hardened off, as the leaves look to be dark green and waxy. Keep it watered and don’t let completely dry out. That said akadama would be a perfect substrate for planting.
When my wife and I collected the one I own we did in mid summer. It had just 2 large structural roots, it rooted and grew amazingly well. To assist with establishing roots I did not prune any foliage the first year. Elongation = root growth. Check out my post pertaining to your topic.
Nice find, it’s got nice bones!