Here is a list of the key events during Pope John Paul II's visit here tomorrow and Sunday: SATURDAY

11 a.m.: Pope arrives by helicopter near Reflecting Pool, is welcomed by Catholic school children and given key to the city by Mayor Marion Barry.

11:10 a.m.: Parade to St. Matthew's Cathedral, up 17th and K streets NW to 1700 block of Rhode Island Avenue NW.

11:30 a.m.: Mass for clergy at St. Matthew's, said by pope.

1:25 p.m.: Parade to White House, down Connecticut Avenue, 17th Street and Pennsylvania Avenue. There, pope meets President Carter and other government officials.

4:30 p.m.: Parade to Pan American Union, down 17th Street to Constitution Avenue for reception by Organization of American States.

6:00 p.m.: Diplomatic reception by pope at residence of apostolic delegation, 3339 Massachusetts Ave. NW. Pope remains overnight at apostolic delegation. SUNDAY

8:05 a.m.: Pope arrives at National Shrine of the Immaculate Conception in Northeast Washington to address 4,000 nuns.

9:15 a.m.: Short parade on Michigan Avenue to Catholic University field house to meet with theologians and other members of academic community.

12:20 a.m.: Short parade on Michigan Avenue to Trinity College for ecumenical meeting with non-Catholic Christian representatives. Also, the pope gives special greetings to several hundred handicapped persons assembled on college lawn.

2:30 p.m.: Motorcade and parade to Mall for papal mass. Parade along Constitution Avenue.

3:00 p.m.: Mass on the Mall.

5:30 p.m.: Pope departs for apostolic delegation, prepares to leave the United States.

6:45 p.m.: Leaves by helicopter from Naval Observatory to Andrews Air Force Base.

7:30 p.m.: Departs for Rome.