Answer by taking a quote from the following article:

Ronald Wilson Reagan was born on February 6, 1911 in an apartment on the second floor of a commercial building in Tampico, Illinois. He was the younger son of Nelle Clyde (nee Wilson; 1883-1962) and Jack Reagan (1883-1941). Jack was a salesman and storyteller whose grandparents were Irish Catholic emigrants from County Tipperary, while Nelle was of half English and half Scottish descent (her mother was born in Surrey). Reagan's older brother, Neil Reagan (1908-1996), became an advertising executive.

After graduating from Eureka in 1932, Reagan drove to Iowa, where he held jobs as a radio announcer at several stations. He moved to WHO radio in Des Moines as an announcer for Chicago Cubs baseball games. His specialty was creating play-by-play accounts of games using as his source only basic descriptions that the station received by wire as the games were in progress.  While traveling with the Cubs in California in 1937, Reagan took a screen test that led to a seven-year contract with Warner Brothers studios. He spent the first few years of his Hollywood career in the "B film" unit, where, Reagan joked, the producers "didn't want them good; they wanted them Thursday".  He earned his first screen credit with a starring role in the 1937 movie Love Is on the Air, and by the end of 1939 he had already appeared in 19 films, including Dark Victory with Bette Davis and Humphrey Bogart. Before the film Santa Fe Trail with Errol Flynn in 1940, he played the role of George "The Gipper" Gipp in the film Knute Rockne, All American; from it, he acquired the lifelong nickname "the Gipper." In 1941, exhibitors voted him the fifth most popular star from the younger generation in Hollywood.  Reagan played his favorite acting role in 1942's Kings Row, where he plays a double amputee who recites the line "Where's the rest of me?"--later used as the title of his 1965 autobiography. Many film critics considered Kings Row to be his best movie, though the film was condemned by New York Times critic Bosley Crowther.  Although Reagan called Kings Row the film that "made me a star", he was unable to capitalize on his success because he was ordered to active duty with the U.S. Army at San Francisco two months after its release, and never regained "star" status in motion pictures. In the post-war era, after being separated from almost four years of World War II stateside service with the 1st Motion Picture Unit in December 1945, Reagan co-starred in such films as The Voice of the Turtle, John Loves Mary, The Hasty Heart, Bedtime for Bonzo, Cattle Queen of Montana, Tennessee's Partner, Hellcats of the Navy (the only film in which he appears with Nancy Reagan), and the 1964 remake The Killers (his final film). Throughout his film career, Reagan's mother answered much of his fan mail.

When did reagan appear on the radio?
After graduating from Eureka in 1932, Reagan drove to Iowa, where he held jobs as a radio announcer