Not only that, it happened a long long time ago. I'm no astronomer; would that be more or less supernovae?
Indeed. They didn't say it happened an "int" time ago. They didn't even say a "long" time ago. They said a "long long" time. I'd have to pull up a copy of the C standard to be sure, but even if the units of "time" are plank times, I suspect the implications could easily be that the story occurs before the big bang.
I suspect you're thinking of a double (floating point). A long long is only a 64 bit integer.
2^64 planck times is 9.9e-25 seconds. Planck times are really tiny.
2^64 nanoseconds is 584 years.