The whole point was to get a map to earth. The map is pretty useless if it has no bearing on the real galaxy.
I do recall them saying that they would find earth when they found the position in space where the sky looked like what it did in the observatory.
"The scriptures say that when the 13th tribe landed on Earth, they looked up into the heavens and saw their 12 brothers." - Starbuck
"There is a place where you can look up into the sky and see the consellations of the 12 colonies." - President
Then there is talk of Lagoon nebula and having a map and a direction.