When should I put up my Christmas Tree?

Depends if it is a real tree or an artificial one

If you put up a real tree too soon then all the little pine needle things will fall off and you'll be left with a twig on Christmas day !

When you feel like it is my vote!  I'm from Ireland and I go home for Christmas every year so I put mine up around Thanksgiving so that I get the feel of Christmas in the run up to going home.  Plus it makes it warm and cosy and festive and i get to spend time in my apt before and after Christmas with it up.  My mum puts it up on my Grandfathers anniversary on the 8th December and I was going to do that but I figure Thanksgiving weekend is as good a time as any becuase its the real kick off to Christmas season!

Trees are being sold around here ever since thanksgiving. If you put it in now, you'll have a nice full month to enjoy it!

Important note - once the year turn, what do you do with the tree? a lot of cities offers a free shredding service in parks - the shreds are used as either compost or soft surfaces in parks - better then just creating garbage and waste.   

Anytime from Thanksgiving and on is more than appropriate!!  MANY people decorate the weekend before Thanksgiving, others in time for Thanksgiving day.  The stores are all set for Xmas the day after Halloween!!  Others wait until the weekend after Thanksgiving or the first week of December.  I personally like Xmas decorations displayed in time for Thanksgiving.