No doubt there will and are people advising you to start an oak bonsai from an acorn --people who don't have an oak bonsai... As the owner of an actual oak bonsai, I would say "skip it. Ain't worth it and won't produce a decent bonsai in your lifetime..."
Presumably you want an oak bonsai because it's an oak and you're after the aged, gnarled character that makes having it worthwhile. You will not get ANY of that from a tree grown from an acorn in your lifetime, or your children's lifetime.
Oak spend the first 100 years of their lives just getting to the stage where they actually HAVE any character in their appearance. Same is true for oak bonsai. That seedling you're growing will require at least a couple of decades to get decent bark. another ten to produce decent older looking branching and top. then another ten to refine. If you have another 30 years (or 40-50--more would be better) GO FOR IT.
If you want an actual oak bonsai, start with mature material. At the very least, find the post oak's sapling children under or near the tree. If there are acorns around, there are oak children around too. Look for trunks that are already 4-9 inches in diameter. Try your hand at collecting them successfully. Even if your first couple of efforts don't survive, you're still 30 year ahead of where you would be if you start with acorns.