I couldn't have predicted how easy it would be for them to learn to read starting with huge vocabularies, and without pressure and tests and measures. When they could read, they knew it because they started reading. The symbols turned to language. When I started reading my vocabulary was very small, and the books we were reading didn't help that. I couldn't read anything outside of that first grade "reader," but the teacher told me I was reading.
Most people have never known a later reader who was bright and confident. I hadn't before I met unschoolers. Three fifths of my family now consists of people whose late reading was not detrimental, and I have made the acquaintance of many others like them.