Five pm is too early to light the Christmas trees; it is not dark yet. The Magic Kingdom tree lighting usually takes place at around 5:30 pm, right after the flag lowering ceremony at 5 pm. Epcot's is closer to 6 pm, something like 5:55. Don't miss them!
It will be interesting to see if there is a tree lighting ceremony at MGM Studios, since there will not be an Osborne Light Display.