Planting in midsummer in hot summer climate like Kansas is never a great idea - too much stress for the plant and a need to pay very close attention to watering. The choice between fall or spring depends IMO on the size of the plant. If a well-developed 1 gallon or larger plant, I'd plant in fall (mid to late September - early October). If not as advanced a plant, I'd pot up to at least a gallon and then sink into the ground before a hard freeze. By spring, the vine's root system should be large enough to plant out in a permanent place.

gardengal: thanks for the info. I will wait and hopefully find a bigger one in the fall.