I have a 12:30 flight out of LAX on a Wednesday.
What time should I leave Westlake Village?
For a domestic flight, 9:15am if you have a car rental to return, 9:30 if not.
We have relatives in Westlake Village, and it's about 50-60 minutes with no traffic to LAX. We've been having more delays in security lately, so I'd make sure you had extra time at the airport.
Are you driving yourself and returning a car? I'd say leave anywhere between 9-9:30 am.
Maybe somebody with daily experience will come along, who knows better. But I have never gone through the 101 405 interchange without a major backup. Google maps says on a Wednesday leveling Westlake Village at 9:00 will take between 1 hour and 1h 50m to get to LAX. That is in line with my experience. So if you want to get to the terminal the standard 2 hours before a domestic flight, I would leave at 8:15 with car drop off and 8:30 without.
If you leave at 8:15 you'd probably arrive at the same time as if you left at 9:15. The traffic out of Westlake Village lightens up a bit after 9:15 and then the 405 generally lightens up around 9:45-10. But leaving at 8:15 you are assured a stop-and-go nightmare all the way.
I suppose it would be a good idea to watch the traffic reports and have the Waze traffic app.
9:00 is fine.