Postecoglou has just five months to assemble a squad capable of being competitive against powerhouses Spain, Netherlands and Chile in the group stage of the showpiece tournament in Brazil.
He will head to Europe in January to check in on a host of players desperate to put their case forward for inclusion in the final 23-man squad.
The Socceroos have just two friendly matches scheduled before arriving in South America, meaning this trip will take on great importance for Postecoglou in selecting his squad.
"I'll hit the road mid-January, get to as many players and places as I can," Postecoglou told reporters on Tuesday.
"I think it's important that I do see some of the players and have discussions as well because there's some pretty critical decisions to make over the next three or four months.
"I want to make sure I make some informed decisions ... we don't have a lot of games but we certainly have a lot to do."
When asked how many of the 23-man squad he had already settled on for the World Cup, Postecoglou said: "Just me at this stage. There's 23 places still up for grabs.
"I say that with fairly realistic outlook on things. While the Costa Rica camp gave me an idea of what I want things to look like, there's still a lot of football to be played between now and (the World Cup) for all our players.
"As I've always said, form and health and fitness will be paramount in that.
"I've got an idea of what it will look like but I think from my perspective, I'm casting the net wide and narrowing it from there rather than the other way around."
Postecoglou said the Socceroos' next game would be in March and will be played in Europe against a South American or European opponent.
Most outside of the Socceroos' inner sanctum have already written off their chances of even getting a point from the difficult group stage in Brazil.
Football Federation Australia boss David Gallop believes the recent appointment of Postecoglou gives the Socceroos some hope of causing a few surprises in June.
But Gallop stressed it would be more than just results which will determine Australia's success at the tournament.
"We've got tough opponents we all know that but we want to play with a hunger and positivity so that at the end of 90 minutes, as (Postecoglou) has been saying, the team we play against doesn't want to play us again," Gallop said.
"If we do that then the tournament can be successful for us.
"Of course we've got aspirations to win games but as much of that is about how we play and the hunger that we play with."
