I have an 11:25 a.m departure out of CDG on a Thursday in April. I'm staying in the Marais district and am planning to use a cab or private shuttle service. This is my first time to Paris, so I don't know the traffic situation. How early should I leave my apartment to get to CDG by 8:30 a.m.? I don't want to use the Metro as I will have my luggage.
I would give it an hour and take a cab; it will cost 50 Euro plus 7 to reserve on the G7 English speaking phone line the night before. It may take a little less time, but that is rush hour and I'd give it at least an hour. Every time we have gone to the airport, it has gone pretty quickly until close to the airport and then been excruciatingly slow the last few miles. The metro doesn't go to the airport.
A cab from the Marais to CDG will be fixed rate of 50€, plus an extra 7€ if you reserve the cab in advance. (You can do so on the G7 Taxi website or call their English - speaking line.)
I would ask for the cab to pick me up at 7:30 if I wanted to be at CDG at 8:30. It should not take an hour, but that way you have a little cushion in case of any problem.
Be sure to look up which terminal your flight is departing from in advance. Sometimes it says on your ticket, sometimes you have to look it up on your airline website. Terminal 2 has several different buildings, from 2A to 2F-- you need to know which one (or Terminal 1 or Terminal 3).
Thank you so much for the responses! I will use the G7 taxi service.
G7 has an app as well.
Enjoy your trip.