Make sure you watch for dates for rates to be released. You will only get it if:
1. They have rooms still available for your dates
2. Only a % of rooms get the discount so even if room available the discount may not be offered.
I have been unsuccessful getting discount over thanksgiving but did once at Easter (40%). If you asked me for your best chance I would say January so keep your fingers crossed.
I am booked at VGF for January and I doubt I will get a discount but I will try anyways.