Just wait and plant it all together, sometime between now and early August or set a small "test plot" off to the side to see what your results would be both ways. Thing is, kale is one of the more cold tolerant brassicas and unless your first frost is completely devastating, the kale will continue to grow even after a mild frost. And besides, the young growth of the kale is what most deer prefer anyway, so you won't be out much other than max leaf tonnage if you wait and plant later. Scott is correct on the bulb production though, they won't likely eat them until after a few frosts anyway, but the sooner you get them in, the larger they will be. A few extra weeks can be the difference between baseball and softball sized turnips.