You have meatballs, bread and everything else. Now you'll need to measure the bread to gauge how many meatballs to put on each skewer. Like a burger, your bread needs to be bigger than the meat when making a sandwich. Fortunately, the meat will shrink so measure out enough meatballs to fill a bun and thread those onto the water soaked bamboo skewers.
Ideally, the meatballs should be stacked on the skewer, not pressed together. They will shrink so you don't want a lot of space between them, but you don't want the meatballs pressed into one piece. Center the meatballs as best you can and get the grill good and hot.