Scottish Premier League clubs gather for reconstruction talks on Monday but there is no guarantee they will hold a vote over a 12-12-18 structure.
The 12 clubs were unanimous in backing the plan in principle before the SPL came to an agreement with the Scottish Football League earlier this month.
But clubs including Dundee United and Motherwell, who were not involved in the latest talks, have since asked for more information before coming to a decision.
SPL chief executive Neil Doncaster warned last week that consensus was needed, as the uncertainty was causing problems finding a new sponsor for the league to replace Clydesdale Bank.
Doncaster told Saturday's Daily Record: "If we don't get agreement then we have to stick with the status quo and that is what people appear to want least of all.
"Everyone appears to agree we need change to refresh the game, so we face stark choices on Monday.
"Either we go forward with 12-12-18 or we stick with what we've got."
The deal agreed in principle with the SFL would see the top two divisions split into three after 22 games.
The plans also include a fairer distribution of income, a merger of the two league bodies and moves towards a pyramid system.
SFL clubs will meet to discuss the proposals on Thursday.