I was planning on having a total of eight books and two half-books.
Book 1, Catlyn Ollivander and The Mana Potion (1991-1992)
Book 1.5, Catlyn Ollivander and The Half-Breed Killer (1992)
Book 2, Catlyn Ollivander and The Wand Licencing Exam (1992-1993)
Book 2.5, Catlyn Ollivander and The Thunderbird (1993)
Book 3, Catlyn Ollivander and The Rogue Deatheater (1993-1994)
Book 4, Catlyn Ollivander and The Silver Shield (1994-1995)
Book 5, Catlyn Ollivander and The Forbidden Forest (1995-1996)
Book 6, Catlyn Ollivander and Merlin's Grave (1996-1997)
Book 7, Catlyn Ollivander and The Fight for Irregulars (1997-1998)
Book 8, Catlyn Ollivander and Merlin's Magic Academy for Irregulars and Wizards (1998-1999)
I had the general direction of where the story was heading very early into writing. For example, the cover has an item that references almost every book. That brings me to what I'm doing now. I will be writing a chapter talking about what my plans were for each book I didn't get to and chapters talking about the main characters and what I was going to do with them. If there's something that doesn't make sense during these chapters, comment and I'll respond.