It began when one of Peter Kovler's friends happened to remark that his birthday was Jan. 30, and did he know it was Franklin Delano Roosevelt's birthday, too, in 1882.

"Why, FDR's centennial is coming up next year," Kovler mused. "I wonder what's being planned."

He found out soon enough: Nothing was being planned. So the 29-year-old former Department of Commerce speech writer decided he would start something himself.

"I was appalled," he said on a visit to a former boss, Rep. Sidney Yates (D-Ill.), this week. "These things usually start cranking up two or three years in advance. For Teddy Roosevelt they had an enormous national committee and special observances in every state and many cities, magazine articles, parties, all kinds of stuff. They did almost as much for Wilson and for Lincoln's sesquicentennial, also in the '50s. But FDR --- nothing. It was an atrocity."

With the help of Yates, like him a Roosevelt admirer, Kovler quickly formed a committee. You always have to have a committee. He enlisted the likes of Thomas (Tommy the Cork) Corcoran, an old New Deal stalwart, W. Averell Harriman, Edward Kennedy, Archibald MacLeish, playwright Arthur Miller, Joseph Rauh, Arthur Schlesinger Jr., R. Sargent Shriver, Adlai Stevenson III, Studs Terkel and the Roosevelt clan.

Things are snowballing. Yates rushed a $200,000 planning appropriation through Congress. Kovler, a wealthy heir (James Beam Distilling Co.) with some free time, was named president of the centenary project. Officials at the Roosevelt Library at Hyde Park, the summer home complex at Campobello Island and the Little White House at Warm Springs, Ga., were alerted. And the Smithsonian, unofficial headquarters for the centenary, already has outlined its most elaborate effort since the 1976 blowout.

For instance, the Museum of American History plans to reproduce the "fireside chat" scene, the White House study from which FDR, the master communicator, took his case to the people via radio. The WPA and other Roosevelt landmarks will be celebrated in exhibit and film. The Museum of American Art, the Hirshhorm Museum, the National Portrait Gallery, Office of Folklife Programs, Smithsonian Associates and the Woodrow Wilson Center plan to take part in the yearlong activites. A postage stamp may be issued. Studies of the current significance of the New Deal are in the works.

In New York State, where Roosevelt as a state senator and as governor, a centennial program is gearing up, with an advisory panel to be formed this month.

"We've asked the president and vice president to be on the committee," Kovler said. "I hope to hear in a few days. Of course, Reagan drew on Roosevelt's speeches in the campaign, and he used to be a supporter." ever since he was a boy, Kovler has been a fan of the man he calls "this century's greatest president." As an under-30, he feels he is something of an anomaly, for, to many young Americans, Franklin Roosevelt is just a name in a history book to be confused with Theodore, an Aquarius along with McKinley, Harrison and Lincoln. For those over 45, he ventured, FDR is still a controversial figure, not so much for his leadership in World War II as for his systematic expansion of the executive branch into a mighty administrative complex, his introduction of the imperial presidency.

"He was always associated with the idea of a compassionate, activist government, an idea that has fallen from favor recently. Some people are definitely ill at ease to be honoring him at this particular time. But in general, the response has been terrific."

Kovler intends to disband the committee after the final celebration, on the 50th anniversary of the Roosevelt inaugural, March 4, 1983. "I don't believe in institutions lasting longer than they have to," he said. "After all, I'm not a public relations type. I've never flacked in my life. I see myself less an entrepreneur than a guerrilla."