My dictionary gives omniportent as
having virtually unlimited authority or influence
or
1 often capitalized : having absolute power over all <Almighty God>
2 : relatively unlimited in power
3 : great in magnitude or seriousness
These definitions of omniportent do not appear to be the logically inconstant defintion that most people here seem to be using [img]/images/graemlins/confused.gif[/img]
You could say that “power over all” includes power over time, but not necessarily.