Should I wait ?

I'm currently just under nine weeks with my precious rainbow baby, I have three little ones and I'd really like to tell them and our family and friends on Halloween by carving out a pumpkin with a baby and letting them figure it out I think it'd be a really fun way for them to find out, my husbands not sure because I miscarried in January so he's a bit worried, I did have a scan at five weeks and everything was in the right place but it was early so Should I wait until I've had my 12 week scan to make sure baby's ok?