Twenty to thirty posts can be a strong voice dataset, but I would not feed them in as one unlabelled pack. Tag each post by audience, goal, format, hook, proof, and call to action. Then ask the model to infer your writing rules rather than copy your phrases. Keep five posts out as a test set and compare the generated drafts against them for tone, clarity, and specificity. If evyAI accepts examples, start with eight to ten diverse posts and compare the result before adding all thirty. Which part matters most for your persona: tone, structure, or point of view?