Well, the thing is- I'm probably already 12-13 weeks along. I'm still breastfeeding my 10 month old, so I only had one light period back in April, and that's what they are going to base the baby's age on. I'm already showing a bit, so it's not like people aren't going to notice.
My hubby is just desperate to not peeve anyone off. He thinks his father should be the first to know ( I don't know why- he never cares) then his brothers and sisters, his mom and nan, then friends. I know his family, and if they find out people have known for weeks and they are just finding out, it's going to hurt some feelings.
You're the one who's going to be carrying the child for 9 months & then giving birth...you win! 
I use this argument for everything! Love it! It's honestly my main reason for wanting to tell everybody. However- hubby seems to be very serious about wanting to wait, I just don't think he quite grasps just how gobby my family really is!!