Another thing to consider if you are getting it serviced, this is the peak time of year for hobby shops. They might be developing backlogs that could cause you to not have it back by Christmas if you don't take it in SOON. (it may even be too late now, depending on the shop and what their backlog vs service personnel ratio is)
Don't worry, absolutely no one ever forgets about their trains until Thanksgiving time and then hopes to have them back in hand by Christmas. No one! 
(kidding of course(a LOT of people do that), the first paragraph was serious though!!)
-Dave
