A mostly-guest-post by my three year old dearie about her growing brother:

“Just forty five seconds
Thirty forty two 
Thirty four sixty sixty
Two and two
One two three four five seconds
That is how long it takes to be a bigger girl.

Forty six seven eight
forty two eight nine ten.

That is how long it will take my brother to become a big boy.”

Suddenly he will claim stairs marauder forts.
He will bud molars
“And I will be big enough to read books”. 
She adds.