For the handful of Montgomery County school employes who must evaluate and schedule classes for hundreds of handicapped students by the first of September, August is the cruelest month.

Vacations are out of the question. Workdays stretch to 14 hours or more. And weekends are spent soothing the parents of new and transfer students or finding new programs and better resources for last year's difficult case.

"We are working overtime with one goal in mind," says Judith A. Kenney, one of Montgomery's leading experts on handicapped students and the supervisor of the county's central placement unit. "Any student who comes to us with a handicap or learning disability, we want him or her to have a seat on that school bus on the first day of school."

That goal is virtually impossible to reach, say Kenney and other school officials, because some Montgomery parents are only now meeting with school counselors, social workers and psychologists to place their children in special education programs. With the placement of handicapped students taking 45 days or more--and with school starting three weeks from today on Sept. 1--some pupils may have to be sent to interim programs.

Still, for an office that works with 1,600 handicapped students each year and about 300 during July and August alone, Kenney's office has compiled an impressive record. Of the 283 cases the office received at midsummer last year, all but seven were placed in classes by the time school started, she said.

"This year, though, the number of new cases is running about 5 percent higher," she said. This week, for instance, officials will try to find room for 18 handicapped students in schools around the county.

While her five-member staff works only with the most severely handicapped students--the disabilities range from learning problems, vision and hearing impairments to emotional disturbances--Kenney recommends that parents of children with any handicap meet with school officials as soon as possible to ensure the youngster is placed in the appropriate program. It can take at least 45 days for counselors adequately to test and devise a program for a child, she said.

"In the summer months, our typical case is the family who moves to the county on, say, Aug. 10. If the child is handicapped and we're short on time, then we try to get him placed in a school that offers an interim service."

Interim services also may offer a short-term solution for more established families, Kenney said. Last week, for instance, officials worked on a case involving a teen-aged girl whose father complained that he had to place her in a psychiatric hospital because of an unreasonably long delay in getting help from the county, Kenney said.

After receiving a series of letters from the father, Kenney negotiated an agreement with the girl's parents allowing her to resume school in September in an interim special education facility.

When a child's handicap has been recently identified--or in those cases that her office receives in the week before school--Kenney suggests working with the local principal to place a child. "There, again, you're looking for the most effective interim solution," Kenney said. "And, obviously, this office and others around the county have a network to handle the emergency cases."

Kenney and other Montgomery County school officials urge parents of children with special needs to call the following offices if they have questions about the coming school year:

* Area 1, which includes Blair, Einstein, Kennedy, Northwood, Paint Branch, Sherwood, Springbrook and Wheaton high schools, superintendent of special services Betty Howard, 649-6400.

* Area 2, which includes Bethesda-Chevy Chase, Churchill, Walter Johnson, Richard Montgomery, Peary, Rockville, Whitman and Woodward high schools, William Curran, special services superintendent, 299-5583.

* Area 3, which includes Damascus, Gaithersburg, Magruder, Poolesville, Seneca Valley and Wooton high schools, acting superintendent of special services Marlene Hartzman, 948-2670.

Parents of handicapped children under 4 years old may call Elaine Lessenco, the preschool coordinator for Montgomery's central placement unit, Kenney said. Her telephone number is 279-3181.

In Prince George's, parents with questions about class schedules for handicapped students should call the office of special education at 952-4107.