Heartbeat teddy bears

I went for a private scan at window to the womb when I was 6 weeks and saw lovely heartbeat teddy bears. My mother in law really wants us to get her a pink/blue one to reveal the gender to them and I would also love one. I have a 16 week scan with them, does anyone know if I can get one then? I’m not sure how many weeks you need to be to get one 🙂 thanks