Eight months after they received President Reagan's budget plan, seven months after they started hearings, two months after Congress told them how much they could spend, members of the Senate Appropriations subcommittee on labor, health and human services and education met to approve their fiscal 1986 budget.

It took all of 30 minutes.

That kind of speed on Capitol Hill can mean only one thing: The deals had been cut in advance.

Despite the long line of lobbyists outside the hearing room, it hardly seemed as though the panel was deciding the fate of $33.3 billion in discretionary spending and signing off on a $108 billion budget. The Sept. 19 markup session drew just eight of the panel's 15 members, who spent much of the session praising one another's work.

At one point, Sen. Ted Stevens (R-Alaska) was herded into the room, looking somewhat bewildered. "I don't think I'm actually on the subcommittee, am I?" he asked an aide. Stevens was assured he was a member.

Subcommittee Chairman Lowell P. Weicker Jr. (R-Conn.) was so confident of the outcome that his press secretary wrote the news release announcing it the day before the meeting. The session came off without a hitch -- the product of long hours of work by the subcommittee's staff, which pored over each program and struck compromises with senators' offices.

It was further proof, if any were needed, that congressional budget-making has become the province of professional staff members, perhaps because they are the only ones with the time and energy to master the details. For each agency head who testifies and each senator who interrogates him, there is an anonymous aide supplying the questions and answers.

The staff's final task, after Weicker had decided on the basic budget, was to whittle down the "wish list," a litany of special requests made by 25 other senators. The 58 items sought by Sen. Daniel K. Inouye (D-Hawaii), for example, took up four typewritten pages. Weicker's aides checked with their boss and marked the approved items with a yellow magic marker; the others were dropped.

No wish list is complete without a request from Senate Appropriations Committee Chairman Mark O. Hatfield (R-Ore.), who got $5 million earmarked for the Oregon Hearing Institute in Portland. The institute is not identified as a separate item, and Weicker's staff had to scramble to figure out which agency will pick up the tab.

Sen. Ernest F. Hollings (D-S.C.) got $750,000 for a physical therapy clinic in Columbia, S.C. Sen. Alfonse M. D'Amato (R-N.Y.) got $750,000 for the Robert A. Taft Institute of Government in New York, a program for civics teachers that the Reagan administration wanted to cut off.

And for Senate Minority Leader Robert C. Byrd (D-W.Va.), there was $4.5 million for the Mary Babb Randolph Cancer Center at West Virginia University -- the amount that was earmarked in the panel's last budget. The National Cancer Institute had refused to fund the school's proposal on scientific grounds, but agreed -- after prodding from Byrd -- to reassess the area's need for such a center.

The institute, not surprisingly, recently reported that Appalachia is a medically underserved area and could use a new cancer center -- a rationale the subcommittee will use to try to make sure the money is spent in the coming months.

Still, many clinics, centers and pilot programs were left on the cutting room floor. But most subcommittee members will live with the results. Weicker's practice is to accommodate as many requests as he can, but he does not like to be challenged after the decisions are made.

"Weicker managed to give people relatively little and keep them happy," said an aide to Sen. William Proxmire (D-Wis.), the panel's ranking Democrat.

The tight-fisted Proxmire sought no home-state goodies; his only request was $151,000 for the Bureau of Labor Statistics to maintain the publishing schedule of the Monthly Labor Review. Weicker granted it.

One does not have to be a senator to have an impact. The administration wanted to cut the $750 million budget for the National Council on the Handicapped, but the subcommittee approved a $15 million increase instead. Subcommittee staff director John Doyle served briefly as the council's first director last year.

Despite the no-amendment policy, some senators at the hearing could not resist a halfhearted pitch for their pet causes.

Inouye asked that $3 million be earmarked for a study of liability insurance. Sen. Mark Andrews (R-N.D.) wanted $500,000 for a pilot program to study abuse of the elderly. But neither pressed for a vote, and Weicker said he would try to accommodate them when the bill comes before the full Appropriations Committee.

Weicker had nixed a grant program pushed by Sen. Arlen Specter (R-Pa.) called the Talented Teachers Act. But Specter gave it one more try. "I had made a suggestion for some $21 million," he said softly. "I wonder if there's any leeway at all. . . . "

Weicker replied that the bill was too close to the Senate budget ceiling to accommodate major new programs.

Sen. Pete V. Domenici (R-N.M.), who helped devise that ceiling as chairman of the Budget Committee, said he would love to boost funding for the National Institute of Mental Health. But he said he would restrain himself -- as long as his colleagues did the same.

"If we're going to start adding substantially more, I will be there," Domenici said.

Domenici will find out whether his colleagues can control their appetites when the bill reaches the full 29-member Appropriations Committee and again when it hits the Senate floor.

Already Weicker has had to draw up a new wish list that is growing by the hour. He has pleaded poverty in a polite form letter to each requesting senator, saying he can accommodate nothing more than an additional $70 million for AIDS research.

The budget battle, meanwhile, has gone into overtime.

Fiscal 1986 -- the focus of the budget debate that has preoccupied the 99th Congress for months -- begins today. After 26 days of hearings, thousands of pages of testimony and plenty of anguished rhetoric, the subcommittee's budget, like most other congressional spending bills, is barely past the halfway mark. And while the Senate bill inches toward an eventual conference with the House, the government agencies it covers will be running on stopgap funding resolutions.

If the bill becomes law in anything resembling its present form, however, one liberal Republican will have helped hold the line against some of the sharpest budget cuts that Reagan sought this year.

Weicker managed to protect such major domestic programs as the Job Corps, the National Institutes of Health, aid to the handicapped and Pell grants for college students. But most of the programs remained at the levels they were in fiscal 1985; this was not the year for the large increases that Weicker won in his first two years as chairman.

Still, Weicker said during the brief markup, it was a victory of sorts. He said he had refused to heed the administration's "message of despair, that human needs should not be met in light of budget deficits."

"The fact remains we are $4.6 billion over the president's request," Proxmire reminded him. "We are facing a fiscal emergency." But even he conceded that Weicker had shown "remarkable restraint." Proxmire made no effort to cut the budget.

If he had, Proxmire would have been soundly beaten; there are enough moderate Republicans and liberal Democrats on the panel to give Weicker a rock-solid majority. And that is why the subcommittee's final session on the 1986 budget drew to a close without a roll-call vote.

"If there are no further amendments," Weicker told his colleagues, "the bill is passed."