I'd be happy if someone would answer my question. Thanks in advance.

Are the following 3 sentences all correct? If so, what's the difference?
I think in A "until now" is redundant.

A: We have been here since 7 o'clock until now.

B: We have been here since 7 o'clock.

C: We have been here from 7 o'clock until now.
1 2
Comments  (Page 2) 
In the case where you are no longer there, could you also say, "We were there since 8 o'clock," or "We were waiting since 5 o'clock and no one showed?"
If you're no longer there and you're describing something completely in the past, I'd say somethign like "We waited there from 5:00 onward and no one ever showed."
Teachers: We supply a list of EFL job vacancies
And you all missed the important point that numbers should always be written out when followed by o'clock. So it should be seven o'clock, never 7 o'clock.
Interesting rule. I'm not familiar with it.

I suspect it's more often violated than observed.

Emotion: smile