"Fair" doesn't seem the right word for the distribution to me. Since you are deciding, which post / comment to upvote, the initial distribution is far from "fair", but rather a very subjective choice, which you are making.
I do trust in you to do your best for having a broad initial distribution - I just wanted to give the choice of your word for the distribution a thought :)
How is it far from fair? How would you describe it? What would you do to make it better?
"Far" was maybe a bit exaggerated. I just wanted to say that it is always a subjective choice, if one person decides, which posts to upvote or not.
I guess this is not that much of a problem though, because after the "initial" distribution the POB gets spread out more and then it should be handled naturally.