Pichameurs

Hello everyone, I am in the begining stages of planning a wedding and I must say its ALOT of work. My fiance and I are working on our list for STDs and invitations. We are both military and our familes are on different coasts (east/west) which we decided to have a destination/cruise wedding. We are both excited and cannot wait!!! My question is (please dont laugh), I wanted to know if there is a such thing as STDs, with out a date, just a month? We havent decided on an exact date, nor have we booked a cruise. The travel agent that we have talked too said when it comes to cruise weddings they cannot gaurantee an exact day, but a month. I dont know where to go with this, can anyone offer any advice? Thanks Pichameurs