I started a dojo with only myself and a gaggle of raw beginners. The trick is not to run a class as if half the students are advanced. In the beginning introduce one or two new technique per class and work on ukemi and other drills. Don't forget to review techniques you have introduced. I developed a complicated cycle to keep me on track but that's just me.
By the way, run the class for you. You will, no matter what you do loose students and eventually gain. Trying to keep everyone perfectly happy (try a little bit) only leads to everyone being unhappy. Aikido by its very nature attracts people with strong convictions as to what it's all about.
Good luck and keep us informed.