The DS for one thing would need A LOT of time to get anywhere at sublight, and as I mentioned before, it would also take years (probably decades if not a century or more) for the Empire or the Republic to chart areas of space of a new galaxy or territory in general to avoid getting lost or colliding into a star.
I'd trust the Imperials to be able to perform a chain of short hyperhops, shorter than the mean free distance between stars, so no risk of collision. A hundred lightyears might take a hundred days that way, but it wouldn't be that big a problem.
...I'd actually think they would launch scouts for each leg. If the scout doesn't return immediately, the next one does a slightly shorter hop. If that one does return, the fleet / the DS at once follows the tested route. That way, 100 ly -> 100 hours (and perhaps a hundred scouts expended, but that's the Imperial way).
And the Empire could always confiscate some star maps from the locals.
Timo Saloniemi