My SIL organised a bbq at their place for friends and family about 2 weeks after their bub was born. It was really relaxed as it was males and females and everyone just getting together to meet their new addition. Some people brought gifts and others brought salads/drinks ect. So it wsn't a baby shower as such, but still a special way to celebrate bubs.

I think its a personal choice, I wouldn't think it was rude, maybe just have a more of a relaxed day than a traditional baby shower.