Telling your kid ??

So , I had an ultrasound yesterday and the heart beat was 170. My doctor told me I can tell my kid because now the risk is really low , and I had a healthy pregnancy the first time , and I’ve never miscarried. I am just used to people saying to wait until 13 weeks to tell. My son totally knows I think because he keeps talking about babies , asked me why my chest hurts (he tried to lay on me and I was like OWW). He also keeps telling people I’m getting a new baby online 😂. I feel like I’m lying now because I really do think he knows. And he’s just like why aren’t you saying anything lady!? So I want to tell him, but was wondering what you ladies think?

UPDATE***** told him and he gave no shits 😂😂😂 he’s like okay ? It’s growing in your belly. That’s cool awe. I’ll change its diapers. And that was it.