Verified answer

I live in San Diego, but I'm originally from Santa Clarita. I take this drive regularly to see family. Personally, I always leave on Friday evenings at around 11:00 PM. That is not a typo.

I hate LA. Don't fool yourself, traffic in LA is its own monster. Conventional thinking says no traffic, but again--we are talking about Los Angeles traffic. If you leave at 7:00 AM, you'll be fine from here through OC. However, once you hit that LA County line at about 8:45 AM, who knows? It's the summer after all, and LA people do not stay at home on weekends. Unless you have to be in Valencia at a specific hour, You'll take 3 hours to get there (assuming you leave from Downtown San Diego as I do).

Saturday northbound is no problem. Most of the traffic is heading south to San Diego for the weekend. Traffic is always tight on the I-5 when you hit downtown LA, but not as bad as a weekday commute.