Good luck on your goals, I have both of them, and they are very useful, I am not going to lie, I would go for Overloads first, because they are a lot more helpful, then you can continue your journey to Turmoil.
The reason why I say get Overloads first, is because you can use Overloads and Piety together, which is an excellent combination, then you can work your way to Turmoil/Soul Split.
Anyways, good luck, if you ever need any help, don't hesitate to ask.
Cheers,
M4A