I'm not sure how long you have to spend in Paris (e.g., time of the CDG-LAX flight the next day) but even with an ontime 1900 arrival, I wouldn't think you'll be in Paris much before 2030 based on my experience. Depending on flight loads, you may be able to change the flight D-1 (there's a very recent thread re: earlier paid ticket.where the change to the 1st connecting leg was free/w.o. repricing at D-1).