I would aim to be at the airport 2 full hours before your flight boards. Takes about 30 min to get to the airport from Disney so work backwards from that. It's probably 30-45 min more than you need but TSA lines are unpredictable. They MAY take those 30-45 min of your spare time, and they may not. With PreCheck you don't have to account for that extra time. With PreCheck we get to the airport an hour before our flight boards and have plenty of time