Generally speaking, anytime you disturb or stress a plant it will spur it to grow. If you rhizomes start growing now, they won't be able to produce enough carbs to offset what they spent trying to grow. (I'm assuming your north enough to have snow.) So we wait until the plant goes dormant and then dig it up to transplant.
Doing it in the spring is best because when we dig it up, the plant is still dormant but when we shove it in the ground and it starts to grow, its at the beginning of the season so it will survive.
That said, if you really want to get it in the ground, go for it. I would just wait until its been cooler than 50F for an extended period to make sure the roots are asleep.