It's exciting whether you know or you don't know! my sister waited and a lot of people hated not knowing because the fun of buying really girly clothing is gone or little cute sports clothing for boys, you're options are limited on what you can buy but they were nervous the scan would be wrong, so it's up to you. I wanted to know what I was having it made me more excited when I found out, it made it more real to me
Its nice to have a surprise and it keeps you and family all excited until the baby arrives. Finding out makes other things easier such as things for nursery, clothes and you can choose a name too. Its entirely your and your partners decision