I thought about this, but I figured that during the first war, the IF probably noticed the Bugger tendency to pull back - move all the queens into one position and try to defend that point.
That determined, they probably drew up battle plans to essentially punch through the Bugger Empire to the homeworld - given Bugger tactics, destroying them there would end it, permanently. Ender's the Xenocide because he wiped out the Buggers, which suggests that all, or a huge majority of the Hive Queens had retreated to the homeworld.
So, even if the homeworld wasn't the farthest world from Earth the Buggers had colonized, they would all retreat to the homeworld to fortify defenses, making it the farthest one important to the campaign.
The IF was building and sending out fleets like this:
1st Fleet/Oldest & Slowest Ships
2nd Fleet/Medium Speed Ships
3rd Fleet/Fastest Ships
This way, even with the headstart, the 3rd Fleet arrives first, the 2nd Fleet arrives next, and the 1st Fleet arrives last.
If anything, the weirdest thing about this approach is that the IF was able to develop build and deploy increasingly faster ships quickly enough, and able to move coordinatedly enough to pull off the campaign in such a short time. It was a pretty huge gamble, looking at it. Technological advancement, the procurement and training of adept commanders, and predictable battle timescale is a trifecta of warfare that's almost never been pulled off, let alone on an interplanetary scale, decades after planning began.
Honestly, I've heard EG is used in Marine Officer training to demonstrate the attitude of leadership, but I'm surprised that the people who chose it didn't go >_> and pass it over upon seeing how, relatively, well and smooth the campaign went in the end - rather unrealistic.
"But at any rate, the point is that God is what nobody admits to being, and everybody really is."