Flying through CDG in France to Palermo Sicily, where do we go through customs?

When you arrive in Palermo.

(I hope you are aware of the difference between customs and immigration.)

Apparently, I didn't distinguish between customs and immigration, which is why I am humbly seeking assistance on this forum. Has anyone made this journey and if so, can they please share in which airport they obtained the Schengen stamp and where they processed through immigration. Thank you.

Correct, big difference between the two processes.

It is virtually certain that in order to travel through CDG airport to your second flight, you will have to go through an immigration gate labelled "All Other Passports." This may be a speedy process, especially if you have a machine-readable passport, and the gate is automated. Or it could be slow-moving booth with a human immigration agent. The delay also depends on where you were seated the plane, although at a peak arrival time (like 8AM, for example), the line will always be long.

Note that an automated entry gate (I've done this in London, but not yet in Paris) doesn't stamp the passport. They must use computers to identify you upon exit. So someone with a business, student, or work visa might want to get in line for a human immigration interview and a stamp.

If you have a single ticket purchase (but two boarding passes), your luggage will be checked through, and you won't see it in Paris. If you have two tickets, or a non-cooperating budget airline to Palermo, you might have to reclaim the bag and check it again. That would mean a trivial Customs line and gateway at CDG, as well as immigration. You might check with the airline website or their telephone line for more certainty.

If you are asking a question about transit time to the second flight, you may wish to give the associated schedule times, and to look up the "official" transit allowance for CDG.

This may be a speedy process, especially if you have a machine-readable passport, and the gate is automated. Or it could be slow-moving booth with a human immigration agent.

Or — fun fun! — it could be a third option, which I experienced in early June: a slow-moving and misdirected line to the e-gates by contract personnel who either aren't really paying attention, or don't know what they're doing, so that lots of people end up in the wrong line for their relevant e-gates and thus have to retrace their steps against the grain and make their way to the other line that they should have been in in the first place, it only the contract personnel had directed them there to start with !

I just came thru CDG on Monday on the Seattle flight with a transit to a flight departing to Milan and the e-gates that day were clearly marked with an American flag (and British and others). The line attendant inserted my passport for me saying the machine was touchy then I stopped at the window just beyond for a stamp.

You didn’t ask but I’ll ask you how much time you have between flights? Is your flight to Palermo on Air France or ??

My Delta plane parked at one of the tarmac spots at M gates so a set of stairs had to be moved into place. We arrived a half hour early at 7:39. I stepped off the plane at 7:50. Loaded onto the shuttle, got off and then followed the signs to 2F for my Milan flight. I walked steadily but did not run. Security when I got to 2F was quick( maybe a 15 minute wait), Immigration had no wait. There were 2 people ahead of me but the guy was still recombobulating after security and was about to lose his pants so they waved me around them. I arrived at my 2F gate at 8:55 after a short comfort stop (but did NOT get sucked into the Longchamp store till I found my gate!!).

I noted the times because some friends were to transit thru with 1h10m which is not enough time. Basically I hit everything right and the transit was a breeze, just is a long walk and a lot of people to move thru in some spots. I’d given myself 3 hours which was good. I’d choose CDG again for a transit.

Your flight from Paris to Palermo is a local (in Schengen) flight. There will be no passport check for this flight, either boarding in Paris nor deplaning in Palermo. You will enter the Schengen zone (i.e., go through immigration) in Paris. If your luggage is checked through to Palermo (ie, your flights are all on one ticket), you will not see it until you arrive in Palermo, where you will go through customs (which is almost always a formality).