You really have to fudge that one. In my mind, the Borg transwarp network didn't yet exist in the 2060's.
I hadn't made the transwarp connection, but I always dissociate time travel from spacial travel. Movement in time has always resulted in arriving at the same place, just at another point in time. Have we ever seen time travel and spacial travel wrapped into one device?
Yes... The Guardian of Forever comes to mind. Good thing the Borg hadn't assimilated THAT
Technically, the time travel you're describing is both temporal and spatial. Planets are constantly moving through space, so when someone uses time travel to go from 24th century earth to 20th century earth, they have, in fact, arrived at a completely different place from where they left. It's just always conveniently so that their target also happens to be present at both places and times.
I suppose the technobabble solution to this would involve some sort of anchoring effect where using a time travel device inside a large system of stars or planets causes you to follow the gravitational pull of that system rather than just staying put in a single point in space.