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.
Best Answer
The phrases all mean the same thing but (1) is the most common in both cases I think, although in most informal usages "I have" would be shortened to "I've".
"I never met you before" is probably quite common before as it is shorter and the meaning is clear.
"I had never been here until now" would be strike most native English speakers as strange way to phrase it, although they would understand your meaning.