Its a very tough choice. Its best to plant it in the spring because the root system would be more established, but you could probably get away with planting it now as long as you give it lots of protection from the cold. There is a chance that it could go into shock and stop growing for a while next spring since it wont have a lot of time to establish, but it should recover if there isnt too much winter damage. Just make sure you dont break any of the roots when you are planting it or that could upset it.
Good luck!
-Alex

I say its fine to plant now. I found a good deal on a Tracy last Fall and planted it just before Halloween. Of course it was in a leaf cage a month later. Nonetheless, its flourishing now. I have also planted a Needle as well as a Med in the last month.

Alex,I plan on digging the hole 3 times as big as the pot it's in,and mixing 1 cup of palm tone into the soil,and stabbing the sides of the hole,so it will be easier for the roots to get into the native soil.I plan on babying it till next spring.It's not the height of the palm that's a problem,it's the width,it's about 6 foot wide to the tips of the fronds also. Jack,I also planted a Mediterranean palm that has 4 trunks on it last week,that's the latest I have ever planted a palm.I mixed in 1 cup of palm tone with the soil with it also.It was root bound in a 15 gallon pot and was probably 80lbs..HD has cut the price of there palms by 50 percent,I've never seen a 7 gallon pindo as big as this one.

I have planted palms in December(believe it or not)not wise but
it worked,this time of year the soil is at it's warmest and root growth is at it's fastest.

The main issue is the weather in fall and winter to come-

Good luck

I say wait, a Trachy will trive in August-October as it likes dry and temperate conditions. A Butia is not as cold hardy but prefers much warmer temps and more humidity.