Also, Will it stunt the vines to let them bear fruit the first year?

They need to develop a sturdy root system before you let them produce fruit.

In SoCal, I didn't fertilize my kiwi. If I had, they might have eaten our 2-story house! They are extremely vigorous vines!

With any sort of decent soil, you will seldom - if ever - need to fertilize any permanent inground plantings. They get what they need from the soil. If the growth starts to slow significantly, the color of the foliage is off or the plant produces few to no flowers, only then will you need to fertilize. You can mulch with some of your aged chicken manure (or any compost if you have it) but that's not exactly fertilizing :-)

They seem to be taking off well, especially the males. I've put them in an ideal location, so it sounds like no fertilizer necessary. I was surprised to find out that peaches, nectarines can fruit the first year no problem. Those are extremely vigorous where I grow them. So I thought maybe Kiwi were the same.