Very personal question on what you are comfortable with. Some people show up very early just in case there are delays somewhere along the route, or at customs etc. Some people do not need that security.
I personally would want to be at the airport around 2 hours for an international flight. But on top of that, if possible, I would take 1 train earlier than the one I actually need to take.
I would want to be there at 16.45, if trains line up perfectly and there is a train at 16.35 and 16.25, I would take the 16.25. In case that one gets delayed, I can take the 16.35.
(Fictive times, no idea if there are trains at these times)
Keep in mind that the schedule for trains from
Disneyland to CDG can be irregular. It is not that there is a fixed schedule of every 30 minutes there is a train to the airport. Usually there are several trains during rush hour, and then less frequent during the day & late evening.