We are a family of three (ages 49, 44, and 14) visiting Florence, arriving Sunday 23 June at about 1:30 PM and departing Wednesday 26 June at about 10:30 AM.
During our visit, the only remaining Duomo-climb tickets are on 25 June between 17:15 (5:15) and 18:45 (6:45). 18:45 is the last time-slot of the day, after the cathedral itself has closed. I've read that it's best to climb first thing in the morning (which we can't do as they're all sold out) or to climb at the very end of the day. No one ever explains why the very end of the day is better than, say, 17:15 or 18:00, the other two choices.
Would it really make any difference which of those slots we choose?