When to tell my toddler?

bergerbride

I am 12 and a half weeks along with my second, and I was wondering if other moms had advice on when I should tell my 4 year old.  I wanted to wait longer, but since we already told all our friends and family, I dont want him to hear from someone else by mistake. If you are a mommy of 2, when did you tell your other kids? TIA!