Sadly you can’t enter on arrival from CDG but you can arrive as early as 5am on he day of departure. If you have a flight at noon whilst the CCR is nice I wouldn’t say it’s 7hrs nice, others would disagree but if you arrived at 8am or 9am you’d enjoy a very leisurely breakfast, and enjoy a few drinks /cocktails.
if you do go mega early they have sleep pods that you can nap in.
Hope you enjoy the Concorde Room and your flight in First.