Adds nothing to a sentence? (See what I did there?)
And adding 'now not' makes even less sense.
I.e.: 'Is now not the time' Is actually just ... 'Is now the time'. Or even 'is it time'.
I am the first to admit my grasp of my native English spelling, grammar and punctuation is not exactly brilliant but even I am getting fed up with (often) questions that have 'now not' or 'not now'. Is it just people trying to be clever? Or thinking they are reinforcing the time?
To me "this moment in time" emphasises a point in history/present/future; whereas "now" simply refers to the present. It may refer to the same thing but the setting frames the point differently.
Now now now, no need for this kind of thing going forward. Time to draw a red line in the sand under it.
After all, it really only happens once in a full blue blood red moon.