24"is just fine.mine is 18" but 24 is fine.
just learn proper techniques with it.
practice moving around your house with it (unloaded)!
remimber barrel pointed downward is preferd to pointing upward!
move from room to room and clearing each room.
develop a plan with your family. knowing your equipment is the key.
if you do not understand seek professional help with home defense!
as with all firearms safety is always first and most important.