My own preference in seeing these intro posts is that they've already posted something or have at least commented. Too often in the past someone would come around, post an introduction, and that was it, not even one comment.

Unless someone's first post is an intro AND they make it really interesting and share their interests along with some convincing evidence they're a real person (and a verification image of someone holding a sign saying Steemit isn't convincing to me), I'd hold off on voting this kind of post.

That said, warm welcome comments from multiple people would be worth far more to Steemit as a whole than upvoting their posts.