Hello Shirin,
In 2011 I travelled from Canada through Paris CDG to St Jean PDP. I came from a different direction but I also arrived Paris CDG in the morning, 7:40 I believe. Conveniently, there is a train station in the bottom floor of the Paris CDG airport. The route is Paris CDG to Bordeaux to Bayonne to St Jean PDP. The train departed Paris CDG at 10:10, so I had 2.5 hours to make the connection, loads of time to find the station, print the pre-purchased ticket, eat, find the platform.
I ended up staying overnight in Bayonne, caught the train to St Jean the next day and arrived there about 12 noon. Met another peregrino on the train, we had a snack in St Jean and then headed up the hill to Orrisson (reservations required) for the first night on the trail. All was exciting and went smoothly.
Good luck and Buen Camino
Eric