Although Formats does not specifically state this (other than where it applies to lists) the intent is that the reader have no problem understanding when a change in print context occurs...so if something ends on line 24 or 25 of a braille page that requires a blank line following it, leave line 1 of the next braille page blank. In this case, it is the centered heading that requires a blank line preceding it...Braille Formats DOES say that a heading can be on line 1 of a braille page if there is no running head (and it does not address what is on the previous braille page). So it IS confusing!
In your case, I would consider how long the centered heading is and whether or not it might cause the reader some confusion as to whether or not it is a change in print context. If it is an especially long heading, I would definitely leave line 1 blank. If it is a shorter heading, there would likely be no confusion due to the number of blank cells preceding the heading so the heading could be placed on line 1.
I'm sorry that there is no specific rule or guideline to support this! The BANA Formats committee is looking into clarifying the rule that relates to text ending on lines 24/25 and I hope that it will take away some of this confusion. For now, you must do what is best for your reader.