It really changes women to women and depends on if its a multiple pregnancy and if you've been pregnant before.
With my first I didnt show til around 16wks I'd say. I'll have to get out the pics.
With#2 I literally POAS and got a bump lol well not that bad but by 8wks you could see it, a little mound not fat (I'd just got to my goal weight and bam, BFP!)
This one, well I look bloated and fat at the moment (7wks), but I've done zero real exersize and not sure I have any stomach muscles anyway any more.
Take at look at the Bump pictures at the tops of the forum, the variety is amazing.
Hope you are well.