Arriving at CDG at 0600. How much time do I need to process customs/immigration and take the train to Gare St. Lazare for a train to Caen.
Two hours is plenty enough to be done with the bureaucracy and waiting for the rer. That ride will be right at an hour. Toss in one more for screw-ups. Four hours.
Traveling alone and light - - and knowing where everything is - - I'd probably make it in two hours, but I'd be sweating a bit.
If you get hot and sweaty, Ed, just strip down to the Speedo.
It must be that time of year again.
Plot out the commute from the aeroport to St-Lazare on the Paris regional transport site http://www.ratp.fr/en/
It will estimate the time needed, although the site optimistically assumes the tourist will not get confused and waste time. You can see the St-Lazare station in photos at the blog www.parisbytrain.com and the RER at CdG too.