CDG - Giverny - Honfleur timing?

In practical terms, it takes about 1.5 hours to drive to Giverny from CDG. How long it takes to get from plane to car is another matter.
It does occur to me that to land from an overnight flight and then have a full day's activities including two drives of 1.5 hours may be a bit ambitious.

Have you traveled to Europe before? Asking because I agree that this is pretty ambitious for your arrival day. Even though I take steps to mitigate jet lag I would not be able to enjoy this start. I don't rent a car in Europe but most who do don't recommend driving that distance after an overnight flight.

I would expect the gardens to be pretty strict about their timed entries. It IS crowded and they need to do something to even out the flow of people. I've always been on time for my visits to the garden so no personal experience with being late.

If you do make your 2:30 entry for Giverny and afterwards (say, 1 1/2-2 hours later), then drive to Honfleur, you will be arriving there possibly when it starts getting dark (Sept.). I wouldn't want to be trying to drive in a different country after an overnight flight late in the afternoon or early in the evening. I don't usually have jet lag even flying from Calif., but I would still not be in good shape for that drive, and for locating my lodging. And have I had any time to eat that day? My body would need some nourishment to avoid flagging out. Viamichelin and Google both give you drive times that I find are not long enough. They don't factor in time to get gas or food or use bathrooms. We always add an hour to what they say. If it is less, then yay! Better to be prepared though.