I didn't know with my first (boy), Iwas team yellow
I did know with my second (boy) as we had small house and wanted to plan , work it out logistically.
I didn't know with my third (girl) as diff hosp wouldn't tell us due to rules, then had late size scan, and they told us
Last baby (boy), having done it both ways, I really wanted that team yellow feeling at the birth again, but at the 20 week scan, we both saw the gender easily, so I guess if wanting team yellow and you have seen lots of scans before- be careful you may nottice what your looking at more!
If I was lucky enougth to have one more, I would prob try to stay team yellow again, but preparing is so much easier if you know what your having. room sharing, decorating , carboots, washing /sorting stuff from loft, colours etc. But knowing at 20o weeks, really breaks up the pregnancy into halves and makes it lovly and exciting. You still have the super exciting moment at birth anyway - who wouldn't be...
Oh any as I knew the gender last time, I didn't have a 3d scan, that way I still didn't know what baby looked like.....