After a cruise ending in Civitevecchia on 10/10, our flt begins at 10am 10/11. Should I start traveling back to airport on 10/10 or do I have time on the 10/11.
October 11 is a Sunday. Trains don't start running from Civitavecchia to Rome early enough on Sundays for your purposes. The earliest you can leave Civitavecchia on Sundays is 06:03 and that will get you to Fiumicino (with one connection) at 07:48. Both legs are on regional trains and those trains don't always run on time. Besides, if you're flying home from Rome, it's wise to be at the airport three hours ahead of your departure time.