2nd first word

I am not sure what to consider his first word....

When he started making noises that resembled words, I think we would say his first word was "dog"; although it was missing the clear "g" sound.

Now that the words are becoming more clear and less interpretation needed, his first super clear word is "book". He says it clear as day with a little accent on the "k". So cute.

So I am calling "book" his 2nd first word.