Is there a timetable for the days when there are no disruptions?
The last train from CDG Terminal 3 to Paris will depart at 10:59pm (22:59) on October 2, 2023. Remember that the RER B train station serving CDG Terminal 3 is located inside the Roissypole building that is between CDG T3 and CDG T1 so you'll have to walk about 10 minutes to get to the train station. There's plenty of signage upon exiting the CDG T3 arrivals area.
Rail line replacement work will occur between Oct 2 and Oct 26, 2023, cancelling all RER B trains between CDG and Paris from 11 - 12pm (23h - 00h) Monday to Friday (but not on Saturday, Sunday evenings).
If you're arriving after 11pm there is a replacement bus service between CDG T3/T1 train station and Aulnay-sous-Bois station where you can take the RER B train the rest of the way into Paris.