Ds9 started school at 5 knowing the alphabet and sounds plus 20 to 30 sight words. By 5.5 he could read quite well and by 6 was several years ahead. Ds7 (who does not like to be taught or quizzed) knew the same number of sight word but not all the alphabet and sounds. He had a slightly slower start but was at roughly the same place on his sixth birthday (after one year at school).
I thought ds7 was going to read at 3 but he had a change in interest.