2014 Wagen,
I posted my buyback date a few posts ago but I forgot that it's basically useless information. Both mine and suesrn3's buyback dates are contingent on the available slots and I'm not talking about others customers reserving ahead of you.
The dealer I chose only offers buybacks on Wednesday. A few other dealerships had different days. suesrn3 probably noticed when scheduling that availability is only offered on Fridays (or maybe Wednesdays and Fridays, for example).
So the best answer to your question is going to hinge on you going through your local dealers and finding out which days they are going to offer buyback slots and then align that with a calendar (and then of course it's all going to be subject to availability of those slots, but this is really the last concern from a list as hopefully I've adequately explained).
You might be able to do this through the site when you get your offer letter. But you can also call your dealerships and ask whoever answers the phone. I first found out about specific days when a sales lady called me to talk about some Passat deals. I told her I was waiting for my buyback still and she told me as an off-hand remark that they were all set up and ready for us and hoped it would be soon (and that it was only on Wednesdays).
That comment made me hop on to the site and peruse the various dealers around me to see how I could best get it done with the least amount of hassle. All the appointments were during normal work hours (at least in San Diego) and none on weekends. I'm a little over a hundred miles from the closest dealerships, my wife works during the day, and I'm taking care of our newborn until next semester. Right now, my best plan is to call VW Roadside Assistance, have them pick up the JSW, and then trail behind in my bug.
I wouldn't call it a complicated scenario but I would plan on a certain level of logistical planning to minimize any inconveniences it's going to cause. I just wanted to clarify that our Dec. 28th and 30th turn-in dates probably shouldn't be read as a "no problem" kind of answer to your question.