Prices for dining going up in Oct?

I have been trying to figure out how much we will be paying for the ADRs I am making online. We are in WDW the second week in Dec, and I keep reading about how prices peak for the seasonal price increase Mid Dec. I would like to know exactly when Mid Dec begins. I just called the dining number to try to ask this (what I thought would be simple question) and got a very unhelpful CM. She acted like she didn’t know what I was talking about, but said something about TS meals will increase in price on Oct 29?? Very confused! Anyone know anything?

Not sure about prices going up but I have called dining and asked for prices with tax for the date of our ADRs so that I had a pretty good idea of what we would be paying for meals like O’hana, etc. I was then able to roughly figure out tip.