Air France Frequence Plus - Flying standby on Air France from LED-CDG-LAX?

I'll be in St. Petersburg this week and my return is booked for Saturday, June 30 as:

Flight 1153 from LED-CDG in Business class (J)
Flight 66 from CDG-LAX in Business class (D)

I'd really like to come home earlier, and I'm wondering if Air France allows for flying standby, and on a different day. I'd really like the same flights, but 2 days earlier, on Jun 28.

This is my first time flying Air France, so I don't have status or anything. And my ticket is booked through my company's travel agency. The agency is usually pretty useless, but I guess in theory they can help.

I don't understand why you want to fly "standby". What you are telling us is that you want to change your reservation to fly 2 days earlier than originally scheduled. So you just change it through AF or your travel agency. The same fare buckets (J/D) must be available for your new flights, otherwise you might have to pay the difference to C or J fare. Some change fees will also surely apply (I believe mostly due to the D fare on CDG-LAX).

Ah, OK, that makes sense. I'll look into changing my ticket. I do have a change fee, but I'm guessing that it's the difference in fare that might make this prohibitively expensive.