S.F.
I dont remember the time frame very well, because my only child is 14 years old now, but when she was little she always seemed to be ahead of other children too. I think it has something to do with being an only child and how much time you put into teaching them an dtalking to them. My daughter was running at 10 months old and she could talk in sentences and carry on conversations before she was 2.
Just keep up the good work and read to him, whenever you can!!