Voyager had had many opportunities to cut their journey short or even directly return home which they did not take. For example, Q tried to bribe Janeway during an arbitration by instantly transporting Voyager to Earth in exchange for a favorable ruling (“Death Wish” S2E18). I am thinking only about opportunities that would ultimately return the existing crew home, not merely reduce the trip.
My thought is the first opportunity the crew had to see their home was with the Sikurian space-folding technology in “Prime Factors” (S1E9). The focus is here is “missed opportunities” considering all relevant factors (including timeline preservation which is actually enforced).
Harry Kim was covertly offered the technology in exchange for Voyager’s literature database. Yet even without that offer, Gath offered the crew to stay as long as they liked, which means they could have studied and duplicated the technology themselves within a matter of years - certainly fewer than the 35 years a one-shot use could have left them with.
Likewise, the Sikurians did not restrict crew’s personal use of the technology. This means in a matter of several years the Voyager crew could literally construct a new base and/or ship 40 years closer to home.
A second question would be: how many opportunities to return the existing crew home has Janeway squandered?