I never remove the decorations, why would I? I mean in june there's only 6 months to Christmas!
But seriously, I put them around 10-15 december and keep them till 10-15 january.
Edit: just read the thread with all the "I don't" and all that. I just make a small tree and 1-2 strings of sparkly stuff around the house, nothing outside, and it's not much as I have an artificial tree, but it's nice to have Christmas, family together, presents etc. I mean seriously, just because you're grown up doesn't mean you can't give and get presents. I give presents to my loved ones. I'm 22, going towards 23 in 2 months, but I still think giving presents is nice, since it makes the face of the one who got the present light up in joy, and that makes me happy