I'm not in your zone so maybe someone else will have the tried and true recommendation. I move all bulbs after their foliage has yellowed. Even when it's half-yellowed sometimes.

I find if I move before top growth has begun there can be a root mass already growing. Which is partially severed during the move.

Originally I moved my entire bulb bed in the summer, like in September, since I was setting up new garden area. The leaves were still green. I believe I lost some of the plants over the winter. But the remaining plants are very strong and are sending out new blooms now.

I'm going to wait until the leaves turn brown to move them.