When to tell people?

Hi. I am new to this site, but I found out just over 3 weeks ago that I am pregnant (and think I am just going into my 8th week). I am going through a dilemma of when to tell people that I am expecting though...my husband, mum, dad and sister know but its becoming really hard to hide it from friends I normally socialise with - they're all aware I'm no drinking alcohol and I've so far blamed it on a dodgy tummy bug, but that can't last much longer and i having to lie.

When did other people spread the word? I would have liked to wait until after scan at 12 weeks to check its all ok, and less chance of MC BUT its stressing me out not being able to tell people so I am really torn (as i'm a really open person about anything else). Any advice would be great!