TGV train CDG to Reims

You have two options:

1. Train from CDG (Aéroport CDG station) to Champagne-Ardenne TGV (outskirts of Reims, linked by tram or local train to Reims proper): only a few per day, but saves going to Paris. Allow about 2.5 hours between landing at CDG and train departure (a bit more if you land at terminal 1).

2. Train from Paris Est to Reims. More frequent throughout the day, but requires travelling from CDG airport to Paris Est, best done by taxi IMO if there's 2 or more of you (56€ flat fare), else by RER B (commuter train) to Gare du Nord followed by a 10-minute walk outside. Allow about 3.5 hours between landing at CDG and train departure.

Option 1 is much preferable but timings rarely work out.