Has it got good roots? if not then you have no chance. The absolute
best way is to keep it in a cool place, preferably out of the house
till Christmas day, and then take it out again on boxing day. What
usually happens is they get warm in the house, and start to grow, but
the roots can't provide sufficient water, they get stressed and die.
Some will survive, but I suspect that is is a very small percentage,
and then only the smaller ones with a good root system. Yours at 6'
will probably not survive I'm afraid.

Mike