The UK-based Takeover Panel, which acts as an independent body to supervise and regulate acquisition and mergers, said this week that the consortium had until noon on 21 January 2008 to disclose a firm plan for a takeover.
The comments follow on from complaints by S&N relating to the takeover proposal.
Failure to launch a successful bid during the time frame would then prevent the consortium from putting forward another bid for six months without the regulator's approval.
The decision could bring the ongoing battle for the brewer to a head, ending uncertainty over the future of some of the UK and Europe's largest beer and lager brands, including Kronenbourg, Fosters, John Smith's and Baltika.
S&N and the consortium both welcomed the deadline.
Carlsberg and Heineken announced in a joint statement that they encouraged the Takeover Panel's decision, claiming it introduced a timetable for any possible acquisition.
"It will focus all parties on the merits of our proposal and consequences of S&N shareholders missing out on a value creating transaction," the consortium stated.
"We urge S&N to open talks with us as soon as possible so we can agree the terms of a formal recommended offer, by the deadline of 12 noon on 21 January 2008."
Carlsberg and Heineken first announced in October that they had formed a consortium to purchase S&N. In a joint statement, the potential buyers said that should a deal go ahead, they would look to split the group's regional operations between themselves.
Carlsberg and S&N, both currently hold an equal share of the profitable Baltic Beverages Holding (BBH) joint venture, which operates in Russia and a number of emerging Eastern European beer markets.
Through the takeover plan, Heineken would control S&N's Western European operations, including the UK market, while Carlsberg would claim full ownership of the BBH.
However, S&N claims that the takeover plans are in direct contradiction with the terms of their joint venture agreement for BBH, which would require Carlsberg to sell its shares in the venture back to the UK-based brewer.
The matter is set to go before the Arbitration Institute of the Stockholm Chamber of Commerce early next year to be decided on, with a vast financial prize riding on the verdict, if a deal cannot be successfully negotiated beforehand.
During the first quarter of the year, BBH posted a 37.1 per cent increase in net sales to €1.3bn during the first half of the current fiscal year, resulting from its continued expansion into the region.