Fairfax County school administrators are expected to announce a tentative wage proposal for county teachers as early as tomorrow, ending nearly two months of salary discussions with the two major teachers' groups in the county.

Although several sources said the announcement could be delayed until early next week, the timing comes as a surprise to many school observers who had not expected any salary agreement until mid-December, the offical end of the teachers' "meet and confer" sessions with administrators.

Three years ago, the Virginia Supreme Court outlawed collective bargaining for teachers and since then educators have developed a formal procedure for meetings between employe groups and representatives of the superintendent to discuss wages, working conditions and other issues of concern to teachers. The object of the meetings is to provide a forum where all points of view can be aired, but the school system is not bound to reach an agreement with teachers on issues.

The "communications procedure," as it is called, sets aside 60 working days from Sept. 15 for teachers' representatives to meet with school administrators. In past years, salary discussions have continued until the end of the 60-day deadline, which this year falls on Dec. 12.

In early October, the teachers' groups were informed by Warren Eisenhower, chief representative for the school system, that the school system wanted to conclude discussions on economic issues by Nov. 15. Schools officials reportedly told the teachers the earlier date was necessary to facilitate the school budget process. The budget proposal for fiscal year 1982 is expected to be released in early January.

Documents obtained this week show that the Fairfax Education Association, the county's largest teachers' group, initially sought an 18 percent salary increase for teachers, plus a cost-of-living increase that averaged about 12 percent.

The rival Fairax Federation of Teachers sought a total increase of 17 percent -- a 5 percent across-the-board increase, plus a 12 percent cost-of-living increase.

Leaders of both groups said those were tentative proposals and do not represent final requests. They point out, as they have in past years, that teachers consistently have lost ground to inflation since 1972.

While leaders of both associations refused to divulge their "bottom line," they indicated that the current proposal from the school system is well below what would be acceptable to their members.

Bill Costello, president of the FEA, says his team of representatives are meeting with school officials on a daily basis this week and are preparing for a meeting tomorrow that could go on around the clock in an attempt to reach an agreement with school officials on economic issues. Costello noted, however, that he expects the discussions to continue if an agreement is not reached.

"We are not taking the position that they will end on Friday if we are not able to reach concensus [on wages]," Costello said earlier this week.

Rick Nelson, president of the Fairfax Federation of Teachers, said federation representatives were scheduled to meet with the school team today, but would be unable to meet all night because they would be teaching the next morning.

Nelson, who said he was unhappy at the prospect of an early end to wage discussions, said it appeared that the school system was "rubbing the noses of teachers' organizations" in the fact that they have a weak position when discussing money with the school system.

The teachers' salary items are considered of special interest to many groups around the county because county employes customarily have received the same percentage in salary increase that the teachers get.

"We have been assured that whatever the school system employes get we'll get the same amount," said Pat Silvey, president of the Fairfax County Employes Advisory Council.