I try to do what I can every day. I don't count how much time it was every time, but I know i sometimes just do some streching and sometimes I go outside and exercise there to get some air. The key to have some time is to prepare the day before: I have my clothes ready and other things needed after exercise, because I don't like hurrying in the morning.
I'm not certain what this is in reference to, but I always try to just do what I can. If that means 8 minutes, then that's fine! Even 2 minutes is great. As long as I'm doing something about my current goal, then that's fine for me.