Hey,
Shaking when just beginning/learning qigong is actually very common, especially when coming from a "weak" state. In fact, the "shakes" in the legs is the most common type of noticeable effect people get. The shakes might last a few practice sessions or so, but they do go away soon. Very intense energy in the hands is another. Gradually, your energy will become smooth and transparent (very subtle, but VERY strong)
Just work though it, you doing good. The "putting off doing it" is part of the energy which the shakes are coming from.
Let's put it this way, if "you" were stale energy living in a body, would you want to leave easily? Think of the shakes from that symbolic perspective. They are in fact the weakness leaving, but at the same time, they are that "lack of motivation" energy. When you actually get to practicing and make it past that part, practice becomes addicting.
As for opening/closing, if you're doing it that short, just spend a minute or so doing it. Opening not to worry about so much, but closing, yeah spend the normal time (about two minutes or so). Qi gong transforms (subtly) the body from a weak one into a strong one. You'll definitely want to work up your time to at least 15-20 minutes to get even more of a benefit from it. However, even 5-10 is good, which is A LOT more than some people do.
~Z
