Stay Away!!!!!
We typically go every year for 2 weeks which are thanksgiving week and the week after. It really starts picking up on Tuesday and by Wednesday evening it is a mad house. The resort lobbies are packed with huge amounts of people trying to check in. To the point we had a room problem in OKW and they could not find us another room on WDW property on Wednesday. We had no room to stay in until they finally received a cancellation at CBR (which was a huge downgrade from a 1 BR Villa). We go to check in and a family next to us apparently now did not have a room. It was ugly!! On Thursday (Thanksgiving) the parks are a complete madhouse. This continues through Sunday and finally kicks back to more managable crowds on Monday after Thankgiving.
Do not go unless you just want to people watch. The wait times will be insane.