There is no good time to travel those freeways during daylight hours. It's hit and miss regarding traffic. But since you're traveling on a Thursday, go as early in the day as you can.
It's about 3-4 hours from Three Rivers to the I-210. You should make decent time until you pass through Valencia on the Grapevine. But once you start heading down towards LA, that's when the traffic can heat up. And driving through Pasadena can be just as bad as driving through the heart of LA and Orange County, just not as long.
Just remember that when you're pulling a TT or driving a MH, take your time and always give the 18 wheelers the right of way.