The advance man was late.

The new man in charge of precise, accurate presidential scheduling was more than a half-hour late--for his own party.

"I figured I couldn't get here ahead of schedule," Michael A. McManus Jr. said, laughing and poking his elbow into a guest's ribs last night at a reception in his honor at the University Club.

About 50 people, many of them White House staff members, slapped McManus on the back and shook his hand to congratulate him on his appointment as deputy assistant to the president in charge of scheduling. A mouthful of a title, it essentially says McManus is a kind of combination travel agent and Indian scout.

"They really are the life blood of a presidential movement," said White House Counsel Fred F. Fielding, describing advance men as he stood in the low light of the lime-green Taft Room. A bar was at the crook of the L-shaped room. At the end of the room, by a small green fountain, were the cocktail regulars--cheese, crackers and liver wrapped in bacon.

"So what do you think, about 20 hours a day from now on?" asked Ambassador Richard M. Fairbanks, a special adviser to the secretary of state on the subject of Middle East negotiations, when he greeted McManus.

"No, that's only a half day," McManus answered with a grin, knowing the job from having worked as an advance man for Richard Nixon's 1972 campaign.

"When the president of the United States goes someplace . . . you are moving the whole office of the biggest business in the world," said Jack Packard, who also worked in the 1972 Nixon campaign. Many others in the mostly male crowd worked with McManus in that election, making the occasion reminiscent of a class reunion, or maybe a fraternity party.

Now McManus will fill the space, but not the shoes, previously occupied by Joseph W. Canzeri, who resigned in February.

"Nobody can fill Canzeri's shoes," said Michael K. Deaver, White House deputy chief of staff with a smile, "because Canzeri never wears any socks."