First start by going to the cruise meets board and seeing if there is already a thread set up for your date. If so join in, if not go ahead and start one.
Yes the meets are organized by the DIS'ers themselves. There isn't one time or place that works for each group. Some like meeting at sailaway, some before the drill, some inside, some out. Figure out what works best for your group and go for it!
If you want to read a bit about what we did for the DVC Member Cruise click on my homepage link (monorailgreen) below and then choose the Member Cruise Scrapbook.