My DS2 is just 2yrs 6 mths old. He knows the alphabet and all the letter names. You can ask him something like "what letter is for whale?" and he will say "w". He absolutely loves letters. He's always reading out letters and asking what the word says. Just a few days ago, he learnt to spell cat. Now he can spell dog and cow as well.
What do you think? Have you any experience of this? I love the fact that my DS2 has a passion for words. However, I'm scared that he'll be bored when he goes to school and knows it all already.