You should probably hang on to it until spring......although what state it might be in then is up for grabs.

It is a warm season grass (looks like miscanthus) and once those produce seedheads in late summer/early fall, they have stopped any growth for the year. It is recommended to NOT plant, transplant or divide warm season grasses in late summer or fall as their roots will just sit in cold, wet soil without growth all winter and the plant rarely survives.

Hopefully it was dug with the rootball pretty well intact, which would assist with its winter in the garage. Check to see that it does not dry out completely but keep only barely damp.

You can plant it fairly early - late March or April or as soon as the soil is workable. Cut back to 4-6 inches at that time.

Thank you ὠA.  I will follow your advice.