I have and idea for a story where everybody has magical potential and at a certain age they must choose a style of magic of where they will base their learning from. Is this too similar to Harry Potter?
Harry Potter by J.K. Rowling inspired authors all over the world to write magical academies. It fine for you to write to the theme but beware that other writers may have taken this idea into several hundreds of hits. Make your own magical education and split factions unique. Divergent is similar to the faction yet it was based on science, dystopian, and romance. Make sure that each person has its own attributes that make them belong in their own group.
Hope this helps.