About "Enabled(Object contributes to the fluid simulation)" I'm sorry, my English is not good.
The following sentences are translated by "Google translate".
Also, I am Blender beginner.

My question is about Fluid-Control.
It seems that Control(gravitational force) is applied in the frame where it is not "Enabled" as marked the image.
The same phenomenon did not occur when the Control was changed to the "Inflow".
Is this my interpretation wrong?
Or maybe my Blender is defective?
In my experience, the Enabled checkbox doesn't seem to give the desired behaviour - in fact, I've just tested this on Blender 2.79.6 and the Enabled checkbox doesn't seem to enable or disable the Control object at all (all it does do is "grey-out" the controls to allow the Control force to be adjusted.

However, instead of keyframing the Enabled checkbox you can enable and disable the effect by simply keyframing the Strength - with zero being effectively 'disabled' and non-zero (higher values for more force) to effectively 'Enable' the control object.

I believe in your example the control object is effectively always enabled.