I can do about 70 minutes worth of instruction, but my well of originality dries up pretty quick after that. Since I don't have the ability to make stuff up on the fly I use the "build on to the next thing" method. I pick a technique and break it down to the essential pieces and start the class on those and work up to the technique. Depending on the technique I'll add in partner work or focus drills with pads.
Teacher mainly just had me slow down and stop focusing on the new guy, but overall he liked what I had to say and how I did it. He gave me a few important hints about time eating drills and how they can fill in between times where I might need to think about what needs to come next. He also had me change content mid stream as I was kind of exhausting the one area (legs in this case) pretty hard.
So this week, while he's still here I'll do the whole class twice before he heads out.
One thing I hadn't counted on was that when you are teaching you don't get to do a lot of doing. I'm going to have to figure out how to do that because I felt like I was missing out on practice. Bummer.