Theoretically it shouldn't matter if it's been indoors, but I personally would like to wait until spring. Unless a tree has been grown only under artificial light it would still be aware of longer or shorter light days and will respond differently.

Thanks Larke! I figured that I should wait. The tree isn't all that healthy either. I just can't stand lookings at it. I wanted to air layer it now, so that it does not die. It has a lot of dead branches.

Air layering a sickly tree in the dead of winter sounds like a surefire way to kill it. I would wait until warm weather and work on getting the tree in better shape in the meantime. Jack