When to tell "big brother"? 👶

Tarra

We have a 3 year old who is going to be an incredible big brother. He's been praying for a baby sister AND a baby brother lol. He plays with "babies" all the time & he's already figured it out we think because he pointed to my belly aaaaannnd said "MOMMY YOU HAVE A BABY IN YOUR BELLY! " We are pretty sure he's just put 2 & 2 together from seeing pictures of other pregnant bellies & my tummy is SUUUUUPER big with bloat lol. I didn't confirm it for him. We saw baby yesterday for ultrasound heartbeat was 172. .i'm only 8 weeks 4 days though. Are yall waiting until 12 weeks? Or 20??? Or until when to tell siblings???