If you can, take an early flight out west. We are also traveling with a 3 y/o. Our flight leaves at 8:25am, and we land at 11:30am Pacific. With how early we have to get up to get to the airport, DD should nap on the plane. If, for some reason, she doesn't, I am pretty confident she'll fall asleep on the way from LAX to Anaheim in the car. Either way, having that nap should be enough to get her to at least 7:30pm or so for bedtime which should help get her on a "regular" schedule in CA that mirrors what her normal schedule at home is (she normally goes to bed around 8:30-9 at home).
On the back end, we're coming back on a Friday so that she has the weekend to readjust to an east coast schedule before going back to preschool.