Inauguration Week opened Sunday with dress rehearsals for Friday's oath-taking and for the parade that will snake down Pennsylvania Avenue to mark the swearing-in of George Bush as the nation's 41st president.

The first sampling of the gridlock that will freeze the capital through the week was relatively painless - few cars or people were out on the damp and cold Sunday morning while units of the nation's armed forces marched down the blocked-off avenue.Just before dawn, inaugural officials, using military personnel as stand-ins, ran through the actual oath-taking on the west front of the Capitol, where Bush and Vice President-elect Dan Quayle will be sworn in Friday.

As they recite the oath of office, Bush and Quayle - and the thousands of dignitaries on the platform - will gaze on the Washington Monument, the Lincoln and Jefferson memorials and the various buildings of government.

Workers were finishing Sunday the huge white platform on the west front lawn.

Thousands of folding chairs were arranged in neat rows down the lawn, and enormous flags were draped over the Capitol.

On the platform will be President and Mrs. Reagan, who will leave for their California home immediately after the ceremony with a ruffles-and-flourishes salute at Andrews Air Force Base.

Traffic was halted Sunday for blocks around the White House to permit the fanfare and parade practice, which included a limousine carrying a "fake" president.

In an interview published Sunday in Newsweek, Bush mused about his transition from No. 2 to chief executive: "It's the old song - do it my way. I did it my way as vice president - support the president, who does it his way. He's ending up with magnificent respect from the American people. Jan. 20, noon up there, then I start doing it my way."

The president-elect, his wife, Barbara, and some members of their family will move Wednesday into Blair House, the newly renovated guest house across Pennsylvania Avenue.

Security near the White House was extra tight because of a suspicious vehicle in the area, one of several that police and Secret Service have examined over the past week. A police dog "froze" Sunday while sniffing the car, but it was later determined that some fluid, likely anti-freeze, caused the dog to react.