I would plant now. Just be careful about watering after the initial replanting of the rhizomes. They more than likely won't need it and it could cause rot if there's any damage from being dug and shipped. When they recover and are showing active growth, they'll be safer. You may live in an area where the natural rainfall is sufficient most of the time. The excessive heat in Texas is the problem. If you can devise a way to give them some shade until the roots get established it would probably be helpful. You may live in a region where the normal rainfall is enough anyway.
An alternative would be to start them off in a pot which is kept in a shady spot and wait 'til it's cooler and then transplant to their permanent location when it's cooler. Here I've often used the potting method because it's easier to protect them from the heat and sun and because it's easier on me
. Usually lots of healthy roots by the time they get in the permanent location. But I live in a very hot, very sunny and usually dry part of Texas.
I would not leave them unplanted and stored. They are alive and it's an unnatural state for them to be in. The sooner they are able to start active growth - whether roots or fans - the better off they will be IMO.
Good luck!
