I think it is very variable. There are so many different things to master. Mine was able to decode early but it took years that she liked reading chapter books. It was clearly vision related, she still does not enjoy books with tiny text but usually in our library there are different editions of the same book so we'll get the one with largest letters. Same happened with note reading.
My ODD is 8. She was fascinated with letters at 1, knew all the letters in english before she turned 2 and had several sight words. She started reading simple phonetic words around 2.5. We moved to a nonenglish speaking country when she was 3. She was really frustrated that she could not decode that language same way than english and stopped reading for few months. Then before she turned 4 she learned to read very well in our other language. While she was able to read some in english she was missing some skills so at 6 we went through "teach you child to read in 100 lessons" book (only took 2 weeks). She was almost 7 when she really liked reading books alone, before that she would get tired fast. Now at 8 she reads our other language really well and english 5-6th grade level. She does not speak native level english so the problem is her limited english vocabulary rather than decoding skills.
Funny thing is that she never learned letter names in our phonetic language. She still knows them in english and she must have zoned out when they were teaching them in school.
