Shower date changed...frustrated

CJ086

So I get a message from my hostess this morning simply saying "be prepared, we changed the date of the shower" ok that's good hopefully they have picked something sooner than 36 wks like the original one, but whatever a gift is a gift and I am thankful either way.  Here's the problem though, I ask when the shower is now...and I am told "don't worry about it" okay...not worried just need to know when to show up, I know where.  A time would be nice but trying not to be too picky here, she then proceeds to tell me that I need to just leave something a surprise. Um all I have done is give guest list, dates I will be definitely out of town, and that's about it.  I mean they asked for the nursery theme but many people have and if we had a registry.  I have no clue how many will be invited, I know the location because that in itself is a gift from a friend.  How is it even remotely ok to not let the MTB know when the shower is? What are they going to do just show up at some point and say hey let's go to your shower?!