Traffic through Geneva is going to be very slow at that time. If you follow the advice given by Palal, your choices are either itinerary B or C. B is going to be slow, but doesn't actually go through the city centre. Remember you are going to have to return your car on the French side, so when you get to the airport, follow the blue signs towards Ferney, and after the frontier (very rarely any checks), immediately turn left (it is indicated but not obvious) towards the airport, French sector.
Following itinerary C is going to add a good 30 km to the trip, but will generally move faster.