Deciding whether to find out the sex of your baby prior to the birth is a very personal decision… which ultimately comes down to choice. Before the late 1970’s (and in some areas even later) mums didn’t have the option to find out and now as times have changed it’s become the norm to know.
The main issue is to ensure that both parents are in agreement, if you’re in the know and your partner isn’t it’s very difficult to mention the baby without referring to them as him/her which would spoil the surprise. There are pros for both choices and really it depends on you and what is most important - a big reveal on the day and having the suspense leading up to the birth or getting you and the house ready and organised for their arrival.
Whatever decision you make there is no right or wrong - just preference!