The first week of practice??

Coach,
What we do during team period without pads is have a walk through of our defensive schemes. Diagram your scheme on a portable white board and Line up the players. You can use the extra players as a scout offense. This way the players can get a handle on what you do. The coaches can make sure you are aligned in the right techniques. You can also put the scout offense in the formations your opponents run so they can recognize and adjust accordingly. Hope this helps and good luck.