You can plant them now. Just don't water til they start to come up. Make sure they are in a well draining area.
The main problem with most gingers is rot. I have rotted a few. I get over anxious for them to come up and water too much. I have a lot in pots that I take in. This gives them a head start since they are slow coming up. But the hedychiums and some curcuma's you can leave in the ground all year.