 Morning is going to be the best time to get going before 10 is ideal. 7 p.m. or later is also a safe bet. Just know this, whenever you hit the road, it's not going to cost you any more to fill up. The national average for a gallon of gas right now, 351, just about what it was this time last year. And the TSA expects to screen more than 3 million air travelers tomorrow.