If we were a betting website, we’d say this will probably release last, but who knows. But if you start out as a vassal, your first goal will probably be to take over your liege's lands, so if that's not the direction which you want to go, an independent start might be better. It adds a decision that you can fire whenever you want to switch your succession laws to either Primogeniture (where the oldest inherits), or Ultimogeniture (where the youngest inherits).
