ACT Chief Minister Andrew Barr set the trend on Monday by tweeting "any boss that sacks anyone for leaving early on Friday to go to the @BrumbiesRugby is a bum," in response to the Brumbies' online campaign aimed at getting more people to the quarter-final showdown in time for the early 6pm kick-off, with the hashtag knockoff4kickoff.

Because NRL club Canberra Raiders have a triple header at Canberra Stadium on Saturday, concerns about frost meant a 6pm kick-off was chosen for the Brumbies-Highlanders final, which could make it tough for some fans to get to the game after work.

Kingston Foreshore pub The Dock will show support for the campaign and the venue's owners, Brumbies players Scott Fardy and Ben Alexander, with free return buses leaving from the pub at 4.45pm. True to tradition, they'll shout patrons a beer if Fardy scores.

Simon Chester, the general manager of ACT Brumbies commercial operations, said more than 60 businesses had signed up for the social media campaign by Thursday afternoon and expected 100 to be on board by Friday.

"The community support has been amazing," Mr Chester said.

"I think it was really boosted by Chief Minster's comments on Monday. If you are in an organisation in the private sector with their strict time frames, you need a pretty good reason to get out."

Around 10,000 tickets had been sold to the match by Thursday afternoon, with Mr Chester hoping for a turnout of 15,000 - if the forecast rain holds out.

Queanbeyan Mayor Tim Overall tweeted his support for the initiative after Mr Barr's comments, writing "Calling all CBR, get behind us and urge your boss to #knockoff4kickoff."

And perhaps some of the most enthusiastic supporters were the teams behind the projected Brumbies logos on Telstra Tower and London Circuit hotel, QT, on display this week.

Much of Canberra's corporate sector were also set to ditch their work uniforms for gold and yellow, as marketing agencies, telecommunication businesses and law and accounting firms showed.

Phil Trenbath from the marketing firm Mark Agency said around half of his staff were cutting their shifts short on Friday.

"Crowd trends in Canberra have shown Canberrans are less likely to go to the footy but the Brumbies need us now more than ever," Mr Trembath said.

David Pembroke, the CEO of content marketing group, contentgroup, gave all of his staff permission to leave at 4.30pm.

"In order to support the players we need to get as many people as possible to the game to create as much noise as possible so they can win what will be a very hard match against the Highlanders," Mr Pembroke said.

The Brumbies are also using free pies and parking to lure a much-needed big turnout.

Coach Stephen Larkham said he was expecting a good crowd.

"The 6pm start is a bit unusual, but it's a good chance to knock off early and get out and enjoy it," Mr Larkham said.