The Trenitalia site has been a little quirky the last few days. As euro cruiser suggested, look up trains for October 4 and simply go forward from there to see the schedule for October 5. I have attached a screen shot for the times you are likely interested in. Note that (with the exception of the Leonardo Express solution, all the changes are at Roma Ostiense. Given the airline arrival and fooling around at FCO on the morning of travel, you should consider purchasing your ticket upon arrival.