BABY SHOWER?!

Baby has been very active kicking his dads hand and rolling all around in mommys belly, starting to feel like an alien is in there. I am 19 weeks along this week, and thurs sept 17th we go in for our ultra sound to find out just what BABY is... a mommys boy or daddys girl. This whole planning for a baby shower is tough... especially with 4 of them to plan. Trying to pull all families together for one BIG ONE?? dont know what is a good idea yet. Please i need input! When is far enough along to have the shower...? Dont know where to start.