Games don't release on Sundays. Friday the 29th could be the last day of the year that their system supports. It's a different system than Amazon's.I can't even remember the last time someone used "Winter" as a timeframe. They usually just say either Holidays or Early <Insert Year>. Again, if they're not sure but their plan was to release at the end of the year, they're not going to say. Because there isn't even a guarantee that a delay wouldn't extend beyond "Winter" depending on the circumstances.
They could get around that by saying "this Winter" or some other period that includes late 2017 and early 2018.
Personally, I wouldn't release on the 29th. If it was going to be that late, I'd just hold off releasing it until tax season. If Sony really is or was wanting to release it then, I'd question the judgement.