Lol I know it is tempting to think a little irrationally, I have already convinced myself I'm having another boy and I'm not even pregnant...! I even have it in my head I'm not a nice enough person to be blessed with one of each...but that is another story! But just remember booking this scan has NO impact on what you have, it either confirms your suspisions early to prepare yourself or gives you an extra 4 weeks of excitement, either way I think it is a good idea. Do you have 3 boys already?