Seeing that you asked this question nine months ago, it is probable that you no longer seek an answer. Could it be that baby has arrived?
At any rate, to my way of thinking, it totally depends, whether you shoud wait to know the sex of the child at birth. The decision to know, or not to know, may vary from child to child. For me it was imperative to be surprised with the first. Not knowing whether the child within was a boy or girl simply added to my great anticipation, and to the excitement of the future grandparents, aunts, uncles and friends. It was wonderful not to know. After the fourth child, and being pregnant with number five, I wanted to know. I had given away, the baby bed, clothes, stroller etc. I had to begin replacing these mostly pink things. So... I wanted to know. Imagine my surprise. I was sure number five would be a girl. I was wrong.
To know or not to know, that is the question. It depends on you and your husband, and only you and your husband. It is your decision to make. I did both and either way was great. I was happy to be surprised on a number of occasions. However, the joy was not lessened by knowing.