When to tell our kids we’re having another??!

Br

So I’m 6 weeks today, had my first scan yesterday, saw the heart beat and baby and everything is measuring great.

My question is, WHEN is a good time to tell our other 5 kids were expecting another?

I want to this weekend but Im not sure if it’s too early...

They’re ages 4, 8, 9, 11 & 12.