I come across different Tenses used with "until now". For example,
1) I have never been here until now. 2) I was never here until now. 3) I had never been here until now.
It goes the same for "before now"
1) I have never met you before (now). 2) I never met you before (now). 3) I have never met you before (now).
I can say that the Present Perfect is what seems to be the least appropriate from a logical point of view but I think it is valid on the basis of its idiomaticity regardless of a logical blockage. Because as soon as you meet someone it changes the situation and your not meeting this person goes into the past. Hence, the Past Perfect is more logical here.
But I would like to listen to your comments where you would express your opinion on whether
1) all the three tenses are used in colloquial English
2) which are the least appropriate
3) and whether they mean the same thing in terms of their meanings.