Congratulations!
First time around we told my parents at about 9 weeks, had intended to wait until first scan, but went to theirs for lunch and couldn't keep it in. Unfortunately, we found out a few days later that there was no heartbeat and I'd had a MMC.
I kind of wish I hadn't told them, they are in their eighties and were so overjoyed and excited about being grandparents, and then three days later I had to give them upsetting news. If I hadn't told them, I probably would've told them about the mmc after the event, but raising their hopes and then dashing them felt a bit harsh.
My partner and a few close friends shored me up at the time, but not my parents because we don't live particularly close to them, and because I'm in my forties, so the idea of my mum and dad supporting me feels a bit weird. Also, although the whole thing was very upsetting, there wasn't really much anyone could do anyway, and I didn't want or need to talk about it. I appreciate everyone is different though.
Nine months later I conceived again, and I can't remember when we told them, I think we waited until I'd had an early scan at 7 weeks and seen a hb. Everything went smoothly that time thank goodness.
Just tell them if you want to, it's not going to jinx anything. But bear in mind that the more people you tell means the more people you have to un-tell if things don't go well - and that's a rubbish thing to have to do.