Don't worry! Find out when the formal nights are after you board the ship. If you book the hairdresser as soon as you can after that then you should not have a problem! Happy cruising.
It tends to be governed by the number of days the cruise lasts and which ship you are on but the norm is only 5 night cruise 1 formal; 7/8 nights 2; 9 to 15 nights 3 and there are also informal and casual nights. Generally a rule of thumb is 3 formal then min 3 informal and the balance is casual. Ships in the NCL group don't follow the norm they tend to be more casual/informal options, but check the brochure or the cruise company. The Sea Princess will follow the options above depending on the number of days at sea. If 3 formal then the 2nd day of the cruise and the penaltimate before leaving with the ship with the 3rd in the middle, tends to be governed by the days at sea.
Difficult to say with real accuracy but I would assume the second day when you visit Rhode Island as you leave a 2pm and the ninth day when you are at sea prior to docking in Quebec. But, as has already been said, it's best to book as soon as you know when you're on board, Reception will tell you immediately. ...Ida.