Is Florence to Rome Fiumicino airport direct train on time always?

I would take the train the night before and stay in a hotel at/near FCO. Most of the time the trains are reasonably on time but you never can tell. Weather, strikes, accidents can upend that pretty quickly.

Just to point out that April 19 is the day before Easter 2025. So expect holiday level travel - would the day before Thanksgiving in the USA be comparable?

If all goes according to schedule, your plan would work. But how easy would it be to recover from a hiccup, never mind a major incident? With the holiday factor, I would choose to be in Rome/airport hotel/town of Fiumicino the night before.

Trenitalia stated recently that 98% of their trains arrive within one hour from the scheduled arrival while 78% arrive on time or within 5 minutes from the scheduled arrival time.

These are the stats. Different people have different levels of risk appetite.

I like to spend the night before my flight in the city where the airport is located (or even at an airport hotel) or at least within 50 km (30 miles) or so from it if I'm driving.

Thanks all for your response.
I didn't realize April 19 is Easter weekend holiday. If that's the case definitely I will stay at a hotel near airport one night before April 19.
Thanks,

I would stay in Rome not at the airport
You have time in the am to get there

Re staying in Rome: Pick a hotel within easy walking distance from a Rome Metro (subway) station a few stops from Rome Termini. Then the day before you just hop off the Trenitalia train and onto the subway to your hotel. In the morning reverse the trip to Rome Termini, then take the Leonardo Express to FCO.

It may be difficult to get a hotel room in Rome, the day before Easter during a Jubilee year. It might be better to enjoy part of the day in Florence, then take a later train and stay out by the airport. I'm not sure you will be able to get much sightseeing in on your one part day in Rome. If staying at or near the airport, just plan to get in early enough to get to your hotel by shuttle/taxi. A friend had booked a hotel nearby the evening before her flight. By the time she got to the airport (she flew from Puglia) it was late enough that the hotel shuttle stopped running and the taxis at the taxi stand were all going into Rome. They decided to wait outside the departures drop off area and found it easier to grab a taxi for the short distance to the nearby hotel. MIght be better to stay at the airport hotel even if it's a little more expensive.

Always be in the town of departure the night before a high stakes trip. Over decades I have had the occasional unexpected delay -- someone jumps in front of the Thalys outside Rotterdam on our way to Paris once and the train came in 5 hours late -- lots of people missed flights. Stuff happens. Usually on time is not good enough when you have an expensive international flight on the line. Come in the night before and spend the night at an airport hotel.