I was there by 5th grade and read grade 5 in first grade. I never read a ton, but I gave cred to my grandma, who would read me "the pokey little puppy" when I was 2 and 3 and 4 years old like every night I was there (a lot).

I had the book memorized and was able to follow along to all the words without knowing how to actually read or anything about sounds. Apparently that was a big leg up in learning to read.