At the table
When Italians eat, and what is open
The restaurant is empty at seven because it is not open yet. Kitchens keep hours, and they are not the ones you are used to.
More visitors are defeated by the clock than by the menu. You can order perfectly and still arrive at a moment when nothing is being cooked, and the polite answer you get, that the kitchen is closed, sounds like a refusal when it is a timetable.
Italy runs on meal times that are narrow, widely observed, and almost never posted anywhere. This is what they are.
Lunch, roughly half past twelve to half past two
Kitchens open around 12.30 and take their last orders somewhere between 14.00 and 14.30. In a city centre with tourists nearby that stretches; in a small town it does not, and at 14.45 you will be eating a sandwich.
Lunch is the larger meal of the day in much of the country, particularly outside the big cities and particularly on Sunday, when it is the meal that matters and can run for three hours.
Dinner, and the reason the room is empty at seven
Kitchens open at 19.30 or 20.00, and Italians arrive after that. A restaurant at 19.45 will be empty or nearly so. The same room at 21.15 is full and loud.
The further south you go the later it drifts: 20.00 is normal in Milan, 21.00 is unremarkable in Naples or Palermo, and in high summer, when nobody wants to eat until the heat has gone out of the day, later still.
If you turn up at 19.00 and find a place serving, look at who is in it. A dining room full of visitors at seven in the evening is a room that has arranged itself around visitors, which is a fact about the restaurant and worth knowing before you sit down.
The gap in the afternoon is real
Between about 15.00 and 19.30 most restaurants are closed, and not in the sense of quiet. The staff have gone home, the kitchen is cold, and the shutter is down. Bars stay open and will make you a coffee and a sandwich; a tavola calda or a pizza al taglio counter will feed you properly. A restaurant will not.
Plan the long afternoon rather than discovering it. If you have a train at 17.00 and you have not eaten, the bar is the answer and it is a perfectly good one.
The day it is shut, and the month
Almost every restaurant closes one full day a week, and it is rarely advertised in a way you will notice. Monday is the most common, because the fish markets are shut on Sunday and Monday fish is nobody's idea of a good time. Sunday evening is the second most common.
In August, particularly around Ferragosto on the 15th, much of urban Italy shuts. In Rome and Milan whole streets of restaurants close for two or three weeks while the city empties for the coast. The places that stay open in a residential quarter in mid-August are doing so deliberately, and are often the better bet for it.
Sunday lunch is the exception to everything
Sunday lunch is the busiest service of the week in most of the country, it is family, and it is booked. Turning up at 13.30 on a Sunday without a reservation is the one time you are most likely to be turned away from a place with visibly empty tables, because those tables are spoken for.
What to do with all this
Book, or arrive when the kitchen opens rather than when you get hungry. Ask the day before if you are unsure, and ask a che ora aprite rather than whether they are open, because the answer you need is a time.
And if you find yourself hungry at 17.30, do not go looking for a restaurant that is secretly serving. Go to a bar, order a coffee and something to eat standing up, and have dinner at nine like everybody else.