To get the finer details, scroll down to the "When to hit the road" section at bottom of Google's report, where it tells you the best and worst times to travel before and after Thanksgiving.
Google Maps says that "between 3 and 4 p.m. [on Wednesday] is the worst time to hit the road, but traffic clears up significantly by 6 a.m. on Thanksgiving morning."
And below that, you can check the expected heaviness of traffic from Wednesday and Sunday. Unfortunately, Google Maps' data doesn't tell which highways or roads experienced traffic spikes.
Like your very own traffic reporter, Google suggests "try your best to avoid the Friday or Sunday afternoon rush and leave in the morning when there are significantly less cars on the road."
Google also registered when crowds were at their busiest during Thanksgiving 2018 at bakeries, grocery stores, liquor stores, movie theaters, and shopping centers from Wednesday to Black Friday, which should give you a good idea of what to expect in 2019. Just don't go anywhere at around noon.