The Hoops finally appointed Neil Lennon's successor last week and the Greek-born Australian will not have long to get his team ready to face reigning champions Rangers, with a trip to Ibrox scheduled for Saturday, August 28.
Postecoglou is already facing a race against time with Celtic's opening Champions League qualifier just five weeks away and a major rebuild required after last year's crumbled 10-in-a-row attempt.
And the former Yokohama F. Marinos manager will have to sharpen his focus even further now that the new top-flight fixtures for the 2021-22 season have thrown up a tricky opening-day trip to Tynecastle to take on Hearts, which will be shown on Sky Sports, plus that early showdown with Steven Gerrard's rampant Invincibles.
The Light Blues lifted their first title in a decade last term and will hoist that historic flag high before kicking off their bid for league crown number 56 when they host Livingston in a televised clash at 1.30pm on Saturday, July 31.
Postecoglou's side will provide the opposition for Robbie Neilson's Championship winners later that day as the Jambos hold their own flag-day celebrations at 8pm.
Play-off winners Dundee will make their own return to the top division after a two-year absence when they welcome St Mirren to Dens Park for a 3pm kick-off. At the same time St Johnstone will look to build on last year's incredible cup double when the travel to Ross County, who will also have a new boss in charge following Malky Mackay's appointment.
The opening weekend is split over two days, with Aberdeen hosting New Firm rivals Dundee United at 3pm on Sunday, August 1, before Motherwell's Fir Park televised encounter with Hibernian kicking off at 4.30pm.
The second round of fixtures on Saturday, August 7 - which are still subject to TV coverage selection - sees Rangers head to Tannadice to face United, who will be looking to make a positive start under Tam Courts, while Celtic host Dundee.
Hibs will welcome Ross County to Edinburgh while Hearts head to Paisley looking to avenge the defeat to St Mirren which effectively relegated them two years ago. Livi host Aberdeen while St Johnstone take on Motherwell.
After last year's behind-closed-doors campaign, club bosses will be desperate to welcome fans back inside and the sight of 10,000 supporters cheering on Scotland for Monday's Euro 2020 clash with the Czech Republic will raise hopes they can finally re-open the turnstiles.
And there will be plenty of big clashes in store over the year ahead.
The return of Hearts and Dundee to the Premiership means Scotland's traditional 'big seven' - which also includes Aberdeen, Celtic, Dundee United, Hibernian and Rangers - are back together in the same league for the first time since 2005.
Hearts have the honour of staging the opening Edinburgh derby of the season, which is pencilled in for September 11, while United and Dundee will renew hostilities after a year apart at Tannadice the following week.
The traditional New Year Old Firm head-to-head is pencilled in for January 2 at Celtic Park, while the big two square off again at Ibrox on April 2. The fourth and final derby of the season will take place after the split.
Meanwhile, the winter break - scrapped by SPFL chiefs last year due to the coronavirus pandemic - makes its return, with the top flight set to shut down for three weeks between January 2 and January 26.