Kathy, Technically and horticultural speaking, It's probably best to leave the Hyacinths until there done blooming and the foliage has browned then move them becuase that's whats best for the plant and it is the easiest. But if your wondering if it could be done and the plant would survive the answer is yes, but you have to be careful becuase the white roots are very delicate, you have to dig a good amount of soil with each bulb. I've transplanted Hyacinths when blooming and they survived. I have to admit though sometimes an irregular planting like you said you have, that often looks the best!

As to the timing your Hyacinths could just be located in a cool spot, shading from trees and buildings could be keeping the soil cooler which can make them a bit later. Doesn't hurt them at all, I have Hyacinths in full bloom near the garage but just buds out further in the lawn. Hope this helps.