I do actively teach DS now at 5 1/2. I probably started when he was about 3 1/2. But before that? We did not teach him anything purposefully. I answered his incessant questions but didn't go chasing stuff or flashcard him.
He's a prime example of nature. He was born early, APGAR score of 0, slow to develop and we were told that hopefully by 3 he'd be "normal" but it was likely that he may not ever fully catch up to average. When he had just a few words, none intelligible to others at 12 mo, the pediatrician said that he'd get it eventually and to just keep talking to him. By 14 mo, he was speaking in complete paragraphs with nearly fully-intelligible speech.
The two things I attribute it to the most is taking him of medication for severe acid reflux and perfectionism. He had been on this medicine from 3 weeks to 5 months old (at which point he wasn't crawling or rolling over). It was like a whole different child appeared in my house about a week later. He was suddenly interested in the world around him, rolled over and began trying to crawl in the same week. And the perfectionism- I've seen it now time and time again. Ds will not present something in "public" until he is certain he has it down perfectly. My guy never toddled... he walked late-ish, but he literally RAN. Same with talking, same with so many other things he does every day now!
