I am not really that sure that homeschooling is the answer to that particular problem. Or at least, it should not be seen as a panacea. (Note: That isn't to say that I don't think homeschooling isn't a good thing, for those with the time/resources/ability/etc. to do so). Unless you are planning to completely isolate your child from society (not just school, but television, radio, various print media, peers, other adults, and so forth), these influences will still get through. Essentially, unless one is willing to raise the child in a crate and feed them through a slit cut in it, societal influences will pay a role.

A better approach is to teach the child in advance how to think critically, and to examine these issues. I don't really think there's a point that's "too early" to start with this sort of thing. While I think the homeschooling aspect does give you more control there, it isn't absolute. And I think that an otherwise involved parent can have enough control to plant a free-thinking seed.

Moreover, I think the idea that a child reared in an environment free of societal sexism, racism, sizeism, (and so on) would inherently turn out to be a paragon of equality. I don't mean to say that they of necessity would not, but there's evidence that it's not something to bank on. Humans are really good at seeing correlations that don't exist (for instance, the women are bad drivers thing). We're also apparently really good at dividing the world into ingroups and outgroups upon even bizarrely meaningless criteria (such as who got heads and who tails on a coin flip), and being biased towards our own groups and against others. It may be 'natural' to be *-ist. Of course, I don't mean to say that it's a good thing. It's natural to die when you get cancer. Part of the glory of reason is the ability to transcend the natural. But to do this, a child needs the intellectual tools to resolve these sorts of situations.