Exactly, that’s all it takes. But, not being an expert, I was sitting here speculating why geologists would think the early Earth’s core wasn’t spinning? The Earth had just formed. Were the interior dynamics of the planet too chaotic at that point or something? I’m glad you asked the question.
Apparently, if there is convection of the outer core not much spin is needed.
I don’t think it would be possible for the core to “start spinning”. It would have been spinning as the earth formed through gravitational collapse.