What sells out first: Christmas/New Years, Presidents Week in February, Spring Break Week in March, Easter Week and July/August sailings when the children are out of school. To get the space you want on the cruise and necessary air arrangements, don't hesitate to book 9 to 11 months in advance if possible. The remainder of February, March and April sailings usually start to fill up once the weather starts to turn cold in the Northeast and Midwest.