iF BRING INSIDE MUST KEEP SOIL DAMP NOT WET & COOL TEMPERATURE JUST ABOVE FREEZING LIGHT WOULD ALSO HELP.
oUTSIDE A COLD FRAME WOULD BE IDEAL OTHER WISE COVER POT WITH SOIL & PLACE STRAW ON TOP. AGAIN THE POTTING SOIL MUST BE KEPT DAMP ALL WINTER LONG

I have no idea where in the country you are located, but I put a little baby Japanese Maple Emperor I, in my basement in November, when it really started getting cold and windy, right in his pot and watered it about once a week all winter long.
In the spring, around May 1, I brought him out, and he leaved out for me and grew fine.
Get him use to the sun gradually though.
If you have a front porch with shade but bright light, it is great for the little tree when he is "waking up" from his winter sleep.
Good Luck!