The body of former vice president Nelson A. Rockefeller was cremated today, the day before a scheduled private memorial service on the family's Pocantico Hills estate in Westchester County, a family spokesman said.

Aides originally said his body would be cremate Monday morning, followed by a private memorial service at 11 a.m. at the family cemetery on the Rockefeller estate. There was no explanation why the body was cremated a day earlier than planned.

George Taylor, a family spokesman, said the cremation took place "sometime Sunday morning at a Westchester crematorium." He would not identify the crematorium or its exact location. "I'd prefer not to, if you don't mind," Taylor said.

Earlier in the day, Taylor said the confusion over the time of Rockefeller's death resulted from the mistake of an aide. He said Rockefeller collapsed in the townhouse he owned at 13 W. 54th St. at 11:15 p.m. Friday, not 10:15 p.m., the time first announced.

Megan Marshak, the Rockefeller aide who was with the former vice president when he suffered the fatal heart attack, telephoned the police emergency number at 11:16 p.m., according ot New York police.

Taylor said Marshak mistakenly had told doctors at Lenox Hill Hospital, where Rockefeller was pronounced dead, that he collapsed at 10:15 p.m.

When that time was made public, it raised questions as to why Marshak and a security guard, Andrew Hoffman, who also was present, waited an hour before summoning emergency help.

Marshak, a researcher who was helping Rockefeller work on a series of art books, lives on the same West 54th Street block as the Rockefeller townhouse.