Well its never established the range of Colonial FTL drives or how far the Red Line is from the colonies.
The nearest black hole to our earth is 1600 light years away (which may still have been functioning 150,000 years ago). Galactica made a single jump from the Colony to Earth.
Unless it was carried their with help from you-know-who...
Actually Galactica had had it's FTL drive upgraded by Cylon tech at that time.