Hello Heather,
Thank you for your question.
In this situation you actually have 2 governing guidelines to consider in determining the use of a blank line.
The first you have already identified which correctly states that a blank line is needed on line 1. (or in your situation line 2 because the book is double spaced.)
However, in this situation you must also consider the guidelines for centered headings BF4.4. This guideline indicates that a blank line is required before a centered heading. So since there is text on line 25 a blank line is needed before the centered heading which in this case is line 1. (or in your situation line 2 because the book is double spaced.)
It is also important to remember that, with the advances in technology, students are often reading refreshable braille and therefore do not have the effect physically turning the page. This makes it more important to have good line spacing to reinforce a format change.
Michael