I think you can transplant some now. I'm not sure how cool it is in your local now but don't wait until it is too hot.

I agree. Anytime when the weather is cool, but never in the heat of summer

I'd do it now (especially if you have a few cooler, rainy days forecast soon) or wait until it is nearly dormant and divide/transplant then. Otherwise, very early spring (usually April in my zone 5 garden) tends to be a great time for dividing.