You don't have to keep track of the durations. If a particular sense feels easy to focus on, you just focus on it longer. On the other hand, if it causes more strain then you should just skip it. As you repeat the cycles they eventually become easier and easier, requiring less efforts. Stop doing the cycles and go to sleep when you begin to encounter a lot of random thoughts.  

Congratulations! That was one interesting LD for sure! :p Physical movements during the cycles do not affect the process. In fact you should feel free to move about if it helps keeping you relaxed. Simply compensate the movement with an additional cycle and you will be fine!