I have flown in on LA with an early AM arrival many times and, although I'm a US citizen and get a different line, if you are near the front of the plane, the line should be quite short when you get to immigration. I believe QF has a big arrival about the same time, but it has never held me up very long. In fact, I usually see people who went to the extranjero line waiting for bags at the same time that I am. Sometimes the customs line gets a bit unwieldy, but usually not more than 15 minutes, and sometimes just a couple of minutes.
I'm not sure if AA has a baggage re-drop just past customs, or if you need to bring it to T-4. In any event, it is a short walk (outside) to the right, around the curve in roadway, to get to AA. Don't take the bus.