Richard Baker wrote:
Why go back to first contact in the first place. The Borg were interested in federation technology, why not visit Earth during the time of 'Q Who?'. Nobody would know what the Borg were still and assimilating the planet might take longer, but that Sphere with the queen could pretty much do anything they wanted to do before the Federation figured out what was going on.
I'm not sure how far this idea actually got, but the novelization has a making of...section and they discuss how an early idea was to have them all travel back in time to the Renaissance. The notion of having the crew running around in Toga's tickled them I suppose. I think the reason they didn't go that route is because a period piece would be too expensive.