Pipero al Rex when to make a reservation
Since the date of your anniversary is what it is, go ahead and make your reservation now and get it off your mind. Ordinarily, for weekends you should reserve as soon as you can, probably not less than a week in advance. For weekdays probably less. Romans don't like to commit too early to things like reservations, so your main competition will come from other tourists researching internet boards. The secret is not to care. If you don't get into Pipero (which I love), try Metamorfosi, Convivio, Agata e Romeo, Il Pagliaccio, and others of that group. You will do fine.