Just to kind of clarify - there is an official start date of the holiday season for a reason. DLR plans to begin certain activities/entertainment on that date each year (Castle/Main Street light show/Carolers strolling the resort/Santa at various locations, holiday parades or fireworks, etc.), and it gives them time to work out bugs and fine-tune everything to make sure it is in working order by the designated date. Keep in mind that this year the holiday festivities are beginning one full week earlier than they have the last couple of years, probably in large part because DLR was technically able to get its holiday attractions and entertainment up and running before the set dates in 2007 or 2008, whether or not they chose to do it. So because everything is beginning earlier this year and is much closer to Halloweentime season ending, there may not be a lot of leeway for soft openings or 'entertainment starting before the start date' kind of thing. We are already one week ahead. And the 'nighttime icicle effect' with the corresponding light show up Main Street to the Christmas tree is considered part of the entertainment.
So while the 700 Christmas trees will be up around the resort and I am sure all the decorations will be in place on the 12th, I don't expect that they will begin the Castle/Icicle/Light show/snow falling on Main Street or other entertainment until the 13th - the actual start date of the holiday season. They may, but I wouldn't think so given how early they are beginning the festivities this year. The Castle will be lit, of course, and will have the 'snow' on it in the daytime, but as I discovered last year with an ill-timed PhotoPass oppportunity, there is a huge difference between the Castle being simply lit up during the holiday season and lit up in the nighttime icicle effect that glows incandescently throughout the park.
