Its a fix it ticket, probably less than 50 bucks.It depends on their backlog. I just bought a vehicle here in LA late in August and it took 4-5 weeks to get the non-vanity plates - I was actually starting to wonder if the dealer failed to send in the paperwork but they said in some cases it can take 2 months. And like you said, there are no true temporary plates like I've had in other states, just the little window sticker on the side window (not back and front windows).
There are lots of people driving around down here without their front plate on and nobody ever gets pulled over for it; most people have the back plate on. Basically, alot of luxury car drivers don't like the look a license plate on the front of their car. I'm sure if you DID get pulled over without plates then you'd get the book thrown at you.