Anyway you could pay a bit more and change your ticket to add on a SAN/LAX flight? Its a quick flight with a beautiful view and beats dealing with the 5/405. With timing for driving, its very hard to say. No traffic, you are looking at right around 2 hours, with traffic it could take 4 hours. I'd say leave about 9am or so. If you get to the LAX airport are quite early, head over to Dinahs Fried Chicken restaurant off of Sepulveda (just north of LAX). You'll have a great lunch and know you wont be worrying about missing your flight.