Yes. This is too risky. Give yourself at least 2-3 hours. You have to be at Ouigo 30 minutes before the trains depart.
And I am a gambling man.

1) I just found out IcelandAir uses Terminal 1 at CDG
2) The CDGeasy website says the transit time from terminal 1 to terminal 2 (train station is there, somewhere) is 20-25 minutes.
3) I've read that we're to be at the platform for a OUIGO train 30 minutes early
That seems to rule out the cheep train.
Right?
Thanks.

Where are you sitting on the plane? You might not get off immediately. That airport is crowded. It is long walk to get off the plane and then walk to the CDGVAL people mover. I would only try to catch that train the day of and not commit 58 euros X 2 in advance

This is not going to happen for you. As you note, getting from Terminal 1 to the train station is going to take you 20 to 25 minutes. That plus the 30 minutes lead time for boarding Ouigo trains rules this out.

*i have edited my post to remove a reference to clearing immigration/passport control; as Bets has correctly pointed out, the OP will do Schengen passport control upon arrival into Iceland. *

It's not possible, as Jazz+Travels and JHK have pointed out.

There would not be enough time for you to disembark, leave Terminal 1 and make it to Terminal 2 for the train station, descend to the train station, and be there for check-in 30 minutes ahead of departure. Not physically possible.

I usually allow for an hour between the time my plane has landed and I am out the front door of the terminal to leave, as a rule of thumb. Sometimes it's faster, but not usually.

I'd strongly suggest booking a connecting flight to Avignon from CDG. The train ride is too long, especially coming off an international flight. The flight should be about 50 euro; you're already at the airport. Air France would be the first place I look, getting the flight added to your current ticket reduces the risk. If you're flight is delayed for any reason, they'll put you on the next plane for no extra cost.

You get your passport stamped in Iceland (takes max 5 minutes), which makes everything easier. Coming into CDG from Iceland (with only a carry on), it takes me right at an hour to walk through the airport and be on a train leaving CDG. If you have luggage, I'm not sure how much to add?

Brad
I tried Air France and Travelocity and neither know of flights to Avignon.

I think your option would be to fly into Marseille, take the shuttle to the city and then the train to Avignon. I don’t know when your travel date is and air fares for that route can be expensive. If you want to get to Avignon the day you arrive, I would suggest taking the 15:37 TGV from Gare De Lyon. It might be more than you want to spend but your choices are quite limited.

I tried Air France and Travelocity and neither know of flights to Avignon.

I have seen Brad mentioning flying from CDG to Avignon several times on the forums as well, and think he's referring to Marseille airport. This is confusing because there is an airport called Avignon - Provence Airport, but it only has seasonal flights to second-tier UK airports (Birmingham and Southampton).

The closest airport to Avignon with commercial air service to Paris is Marseille Provence Airport (50 mi/80 km from Avignon), from which Air France operates flights to Orly and CDG.

This bit of info doesn’t change your tight timeframe but to clarify: you go through passport control in Iceland, not CDG. You would go through security for a flight from CDG but not for a train.

Thank you for "slowing me down."

Q: Do any of you have experience (or a "trust level") in taking a morning train from Avignon to 'directly' to CDG airport on the day of our departure? I think that is foolish, so that's why we wanted to get south ASAP.

I would point out that there isn’t actually a 30 minute rule with Ouigo, although they try to present it as such to get as many people as possible to arrive before then. Officially, they will refuse you access to the platforms if you are within 5 minutes of departure. So, not specific to this but don’t think they’re going to deny you entry if you arrive 29 minutes before departure.

In any case, you still have a high probability of not making the train given flight issues, gate issues, passport control (although actually I don’t think this is the case, you clear in Iceland), and getting from t1 to the trains. Why not take the 17:03 Ouigo departure? The train ride to Avignon is not that long and you can sleep on it. I’m not sure booking a flight makes much more sense, still need to leave a gap between arrival and departure then take train back from marseille to Avignon. It would be a hassle and probably take as much time.

It is possible to make the train if everything goes right and if you clear immigration in Iceland which I think is the case since it’s a layover flight?

I am risk-averse when heading to an airport, and especially so when it's for a transatlantic flight. It would probably cost a lot of money if you missed your return flight and had to pay the walk-up fare for a last-minute one-way ticket home. Someone on this forum has posted about being on a TGV heading toward Paris that had a multiple-hour delay, I think due to a suicide on the tracks. The poster was fortunately not one of the many people on the train headed to CDG for same day flights that they missed.

And trains sometimes get cancelled--not always because of strikes, which are usually announced ahead of time so you can work around them.

we took the TGV from Avignon to CDG and then spent the night near the airport. It felt much more relaxing then trying to worry about making it to the airport in time the day of the flight.