Well I was wrong, WAY WRONG. I figured that the castle decorations would go up fairly quickly and therefore not start until next spring, but like WDWCPBrandon, I saw that castle on Tuesday with one tower turret worked on. I was told by a manager that is working on this celebration (one I know well) and he said it was just a test, but the final will most likely look very close to this test. And when the test is taken down, the final will most likely go up at the same time so there will be no down time.
I only saw it at night during the Very Merry Christmas Party, but I was not impressed by it. It looked like the castle was TP-ed all over again. I have not seen it during the day however when you can see the colors. I do like the concept art though so we will see how it turns out. The one thing I was surprised by (and which is probably why it will take longer to put up) is that the ribbons are not touching the castle. They are being held out about 6 inches from it is it looks like it is floating. I thought they would just wrap the castle up, but they are actually mounting things into it. A nice touch to make it look more enchanted.