Whatever you decide don't delay in setting up your bookings. July being peak season and many ships already filling for holiday dates you may have limited options already for keeping your group together. Get with the cruiseline of choice or preferably a good T/A that specializes in groups and get started. Be sure when you do call you have legal first and last names for all pax as well as DOB for each. That way you can put a courtesy hold on the cabins you want while you finalize the details with your group. The hold will be short term so be sure your group is ready to finalize the booking within a day or two of the hold.