It was a day to take stock of the changes as well as to burnish the memories. Twenty years ago Johnny Williams was, by his own admission, a violence-prone black teen-ager who believed more in "Burn, Baby, Burn" than in "I Have a Dream."

Yesterday, he was one of the first to arrive for the 8 a.m. prelude to the march for jobs, peace and freedom. Williams, 34, now a copy machine salesman, said he had been wrong to reject the message that had failed to move him then.

"I didn't understand peace and love," he said.

In 1963, Williams recalled yesterday, he looked up to the Black Panther Party instead of the Rev. Martin Luther King Jr. and blamed whites for the problems he knew in Cleveland growing up in a poor working class family. Maturity and experience and a college education, he said, combined to convince him that the American dream is within reach.

Williams, now married and living in Forestville, Md., works both a full- and a part-time job. He's starting a computer services firm. Being involved in the political process, he said, is the best way to achieve change. But he stresses that blacks must be willing to work and to demonstrate for that goal.

Thinking about King, the man whose ideology he once rejected, Williams said yesterday, "I thought he was a great speaker, a great minister, but I just didn't understand."