I am staying at the excel Roma ciampino. I have 11entry time to the Vatican. Due to the distance how early should I leave the hotel?
Your hotel would probably be the best resource for that question. And they'll be able to tell you exactly how to get there. Good luck.
Ask the hotel about travel time. Take a taxi at least going (have the hotel call for one). We found the taxi fares to be quite reasonable when combined with what we saved using the metro and/or walking.