I’ve also flown in and out of FLR Many times. My last experience at FLR airport is very recent: about 15 hours ago.
Check in positions open exactly 2 hours prior to departure for all Schengen flights (for Non Schengen flights like London, it is probably 3 hours). I got to the airport a bit earlier for my flight to Lisbon where I am now, and I had to wait till they opened 2 hours prior. That was confirmed by an airport staffer. That rule does not seem to change from airline to airline, as the people working at the desks are not airline employees but employees of “Toscana Aeroporti”, the company that manages the airports of Florence and Pisa. So the check in desks opening two hours prior is standard for all Schengen flights out of FLR. That has always been the case every time I flew out of FLR also in the past.
Don’t be worried if you see a long line early even before they first open the check in position. They first start with one position open 2 hours prior to departure. But then more positions open as the time passes, and the line goes very fast as you approach the time of departure.
I had not flown out of FLR for a few years, but post Covid the airport has become now very busy and too small for the amount of passengers. The security line was fast, but every departure gate was packed and all seats are taken as the gates area is small (all 11 gates except for gate 1 are in the old terminal building). Between the security check and the gates there is a larger duty free shopping area, so hang out there and shop before getting to the gates.
The boarding starts earlier than in other airports as the boarding process always entails a bus ride airside from the gates to the airplane parked on the tarmac. FLR does not have jetway bridges, so boarding still consists of the old style climbing of stairs to the plane after the bus ride (if it rains you get wet too in the process).
I’ve been following the vicissitudes of the new airport and new runway plans for many years now. Unfortunately the process is still stuck in courts due to the opposition of local NIMBYs and environmental groups, so the the project has been delayed for years with more and more environmental impact studies.
This is the rendering of what the new airport is supposed to look like (if it will ever be approved):
www.associazione-aeroporto-firenze.it/wp/wp-content/uploads/2025/02/Aeroporto-110.pdf