Every school(or even coteacher for that matter) is different in what the expect from their native teacher. If you are pretty much doing the majority of teaching and lesson planning for the classes(which really is not how it's supposed to work), I would recommend combining some materials from the textbook...i.e. Look and Listens, Listen and Repeats, Let's Read, Let's Write with your own materials or some from this and other websites. I would say my coteacher and I spend about 40% of the time using textbook and 60% using supplemental powerpoints , worksheets, and games not from the textbook.
The first few weeks are rough, but you will get in a groove and it will be better! Good Luck