As former cross-class actions, the right to add more actions is earned by leveling. It seems we gain them at lv. 12, 20, 32, 40 and 48. Also, it seems it is possible to put in the first slot (lv. 12) an action earned way later (not unlike SCH and AST putting now Stoneskin in their first cross-class skill at lv. 10 when WHM must wait lv. 34 to use it).
