The last several years it's seemed extra bad starting at least a week out. I typically fly out between the 17th and 20th and I think last year got stuck in nightmare traffic already on the 105 and ended up having my driver drop me at the cell phone lot and walked to T7. The year before (or maybe one earlier?) it took an hour for the FlyAway bus I was on to get from stuck in traffic lined up to exit at Sepulveda to T1. I went from having what seemed like plenty of time to nearly missing my flight. Give yourself lots of margin and consider getting dropped off somewhere outside the airport north of Century and walking as a backup.