There are lots of pre-made lesson plans out there, some for sale, some free. Make sure what ever lesson plan format you choose is the same as one of the examples in the FOI. I tried using lesson plans written by others and found it difficult to match my knowledge with the plan written by someone else. In the end I chose one of the simple lesson plan formats from the FOI and did my own. I'm glad I did because during the CFI checkride oral the examiner had me prepare a lesson plan on a subject for which I didn't have anything prepared, upgrading to high performance aircraft or something. He gave me 30 minutes to prepare for the class including writing a lesson plan. I had lots of practice writing lesson plans so it wasn't much of a problem. I think if I had been using the boiler plate lesson plans I would have been in trouble.